breast cancer Flashcards

Question

what is the TNM and survival rate of stage Iv, metastatic

Answer 1

TxNxM1 | 15%

Answer 2

• Surgery o Partial mastectomy for localised tumour o Total mastectomy (removal of all breast) if tumour has spread. Lymph nodes may be removed if tumour has metastasised. • Radiation therapy • Chemotherapy • Hormonal (biologic) therapy o If tumour has hormone receptor involvement (ER & HER2), effects/ formation of oestrogen is blocked.

Answer 3

The cell cycle (cell-division cycle) is the process by which a single mother eukaryotic cell gives rise to two identical daughter cells. Most cells have a finite capacity for division and can become senescent at any time; senescence is the process by which cells irreversibly stop dividing and enter a state of permanent growth arrest without undergoing cell death. Senescent cells sit within the tissue and change the plasticity of the tissue – the longer they sit around, can be promoting a cancer.

Answer 4

The cell cycle is composed of interphase (G₁, S, and G₂ phases), followed by the mitotic phase (mitosis and cytokinesis), and G₀ phase. During interphase, the cell grows and makes a copy of its DNA. During the mitotic (M) phase, the cell separates its DNA into two sets and divides its cytoplasm, forming two new cells.

Answer 5

is a group of genes that encodes a family of transcription factors (TF) in higher eukaryotes.

Answer 6

G1, s and G2

Answer 7

During the first gap phase, the cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps. The availability of growth factors controls the animal cell cycle at a point in late G1 called the restriction point; if growth factors are not available during G1, the cells enter a quiescent stage of the cycle called G0.

Answer 8

The cell synthesizes a complete copy of the DNA in its nucleus. It also duplicates a microtubule-organizing structure called the centrosome. The centrosomes help separate DNA during M phase.

Answer 9

During the second gap phase, the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis. G2 ends when mitosis begins

Answer 10

During the mitotic (M) phase, the cell divides its copied DNA and cytoplasm to make two new cells. M phase involves two distinct division-related processes: mitosis and cytokinesis. • In the prophase of mitosis, chromosomal material condenses to form compact mitotic chromosomes. The cytoskeleton is disassembled, and mitotic spindle is assembled. • In the prometaphase, the chromosomal microtubules attach to kinetochores of chromosomes and are moved to the spindle equator. • In the metaphase, chromosomes are aligned along the metaphase plate and are attached to both poles by microtubules. • In the anaphase the centromeres split, and chromatids separate moving the chromosomes to opposite single poles. • In the telophase, the chromosomes cluster at opposite poles. The nuclear membrane assembles around the clusters, with daughter cells formed by cytokinesis. Non-mutagenic replication of every nucleotide once per cycle is essential; only one copy should be made, with no mutations.

Answer 11

• Purines: o A - adenine o G – guanine • Pyrimidines: o T - thymine o C - cytosine

Answer 12

Radiolabelled nucleotides (3H-thymidine) are incorporated into cells at DNA replication. Using X-ray photography or antibody staining, cells in S-phase may be identified. Flow-cytometric detection of cells stained with DNA dyes allows the discrimination of cells with variable DNA content. Cells in G1 phase (peak 1) contain half the DNA of cells after DNA replication in G2 and M (peak 2); cells in the process of replication (S-phase) contain an intermediate quantity.

Answer 13

In order to drive the cell cycle forward, a cyclin must activate or inactivate many target proteins inside of the cell. Cyclins drive the events of the cell cycle by partnering with a family of enzymes called the cyclin-dependent kinases (Cdks). A lone Cdk is inactive, but the binding of a cyclin activates it, making it a functional enzyme and allowing it to modify target proteins.

Answer 14

Cdk1 is the only on required to drive through the cell stages. Cyclin B1 and A2 are essential for normal cell cycle. • At G1 phase: CDK 4 & CDK 6 binds to Cyclin D – Cyclin D levels are influenced by extracellular signals (mitogens, growth factors and survival factors). The main target of CDK 4 & 6 is Retinoblastoma protein (Rb). Dysfunction of the Rb protein (stuck in on position) may lead to uncontrolled proliferation, where mutations are likely. • G1/S phase: CDK 2 binds to Cyclin E • S phase: CDK 2 binds to Cyclin A • M/ G2 phase: CDK 1 (aka Cdc25) binds to Cyclin B1 • CDKs are activated by activating phosphorylation of threonine around position 160. • CDK-inhibitors are proteins that bind to CDK-cyclin complexes and block their activity. o Wee1 kinase inhibits phosphorylation of threonine 14 & tyrosine 15 on CDK 1, inhibiting cell cycle progression o CDK 1 phosphatase reverses the change of Wee1, leading to active CDK.

Answer 15

The availability of cyclins controls the activity of CDKs and promotes cell progression. CDKs become active via cyclin-binding; when complexed with M-phase cyclin, mitosis machinery is triggered, when complexed to S-phase cyclin, DNA replication is triggered. There are also several checkpoints which ensure complete genomes are transmitted to daughter cells, and cells with damaged DNA do not replicate.

Answer 16

•At G1, cell size, growth factors & DNA damage are checked. If the cell doesn’t meet the requirements, it will leave the cell cycle and enter a resting state – G0. oDNA damage causes p53 levels to increase, causing transcription of p21 op21 binds to PNCA – a component of DNA replication machinery – preventing its activity oBy ensuring that cells don't divide when their DNA is damaged, p53 prevents mutations; when p53 is defective or missing, mutations can accumulate quickly, potentially leading to cancer. Indeed, out of all the entire human genome op53 is the single gene most often mutated in cancers . •At G2, un-replicated or damaged DNA are checked. If errors or damage are detected, the cell will pause to allow for repairs. Topoisomerase II is responsible for repairing DNA at this stage. If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted, and the cell attempts to either complete DNA replication or repair the damaged DNA. If the damage is irreparable, the cell may undergo apoptosis, or programmed cell death oA signal is sent to a series of protein kinases, which phosphorylate and inactivate Cdc25 oThe dephosphorylation of M-Cdk is blocked, and it does not activate, preventing entry to mitotic phase • At M (aka spindle checkpoint), chromosomal misalignment (i.e. the chromosome is not attached to the spindle) will stop the cycle. If a chromosome is misplaced, the cell will pause mitosis, allowing time for the spindle to capture the stray chromosome.

Answer 17

PI3K signalling is a form of endocrine signalling. The pituitary releases growth hormone, which acts on tyrosine kinase receptors. A kinase is an enzyme that transfers phosphate groups to a protein or other target, and a receptor tyrosine kinase transfers phosphate groups specifically to the amino acid tyrosine, activating it. The signal relay pathway through PI3K, PTEN, AKT, mTOR and S6K1 or 4EBP results in gene expression & cell proliferation. The PI3K/AKT/mTOR pathway is an intracellular signalling pathway important in regulating the cell cycle. In many cancers, this pathway is overactive, thus reducing apoptosis and allowing proliferation. In many kinds of breast cancer, aberrations in the PI3K/AKT/mTOR pathway are the most common genomic abnormalities (e.g. PIK3CA gene mutation).

Answer 18

HER-2 is a member of the human epidermal growth factor receptor (HER/EGFR/ERBB) family. The HER-2 receptor is a transmembrane tyrosine kinase receptor that consists of an extracellular ligand-binding domain, a transmembrane region, and an intracellular or cytoplasmic tyrosine kinase domain. It is activated by the formation of homodimers or heterodimers with other epidermal growth factor (EGFR) proteins. Further downstream molecular signalling cascades are activated, such as the Ras/Raf/mitogen-activated protein kinase (MAPK), the phosphoinositide 3-kinase/Akt, and the phospholipase Cγ (PLCγ)/protein kinase C (PKC) pathways that promote cell growth and survival and cell cycle progression.

Answer 19

When growth factor ligands bind to their receptors, the receptors pair up and act as kinases. The activated receptors trigger a series of events: • Ras is activated o KRAS ( K-ras or Ki-ras) is a gene that acts as an on/off switch in cell signalling. When it functions normally, it controls cell proliferation. When it is mutated, negative signalling is disrupted. • Guanine nucleotide exchange factors (GEFs) are recruited • GEF becomes capable of interacting with Ras proteins at the cell membrane to promote a conformational change and the exchange of GDP for GTP. • Raf is recruited to the cell membrane, and activation stimulates a signalling cascade by phosphorylation of MAPK which successively phosphorylate and activate downstream proteins such as ERK1 and ERK2 • Transcription factors are activated promoting cell growth and division. Over-expression of this oncogene has been shown to play an important role in the development and progression of certain aggressive types of breast cancer. The protein has become an important biomarker and target of therapy for approximately 30% of breast cancer patients. HER2-positive breast cancer has a faster growth rate than HER2-negative.

Answer 20

488 (1%) genes are implicated in the development of cancer. Of these, 90% have somatic mutations; 20% have germline mutations (10% have both). Somatic mutations occur in a single cell and are not passed to offspring; germline mutations occur in gametes and may be inherited by the offspring of that cell, affecting many different types of cell. Cancer cells behave differently than normal cells in the body, related to cell-division. Cancer cells may multiply without any growth factors, or growth-stimulating protein signals.

Answer 21

Mutations stimulate cell survival and proliferation, and may be: • Dominant (gain of function) – a single mutation event creates oncogenes - overactive positive cell cycle regulators. • Recessive (loss of function) – two, or more, mutations eliminate tumour suppression activity - inactive negative regulators.

Answer 22

Oncogenes drive abnormal cell proliferation. They may represent the overactive form of normal cellular genes, called proto-oncogenes or alternatively, they may enter the cell as part of a virus. A proto¬-oncogene may become overactive and be converted into an oncogene due to mutation in coding sequence, gene amplification or chromosomal rearrangement.

Answer 23

Tumour suppressors are genes that normally inhibit cell proliferation and tumour development. In tumour development, tumour suppressors are often lost or inactivated, usually requiring 2 mutational events; inactivation can occur through deletion, point mutation or epigenetic changes (where the gene does not mutate but is inactivated). This may occur due to nondisjunction, giving rise to unequal mitosis; random elimination of a chromosome results in recessive mutation of tumour suppressor.

Answer 24

There are 3 types of tumour suppressor: • Caretakers – promote gene stability & control mutation rate o Checkpoint genes (p53) o DNA repair genes (BRCA) • Gatekeepers – monitor cell division & death o Cell cycle (Rb) • Landscapers – control cellular microenvironment

Answer 25

During and after diagnosis and treatment, almost 50% of cancer patients report anxiety and 25% report significant anxiety; 20% experience transient or long-term depression; and 15% are diagnosed with post-traumatic stress disorder. Stress results in the production of the stress response hormones: cortisol, (Cort), norepinephrine (NE), and epinephrine (E) at physiological concentrations. Stress hormones can rapidly induce DNA damage and interfere with the DNA-damage repair process in pre-cancerous cells leading to cell transformation and tumorigenicity. They increase levels proteins involved in cell cycle regulation and progression and reduce levels of proteins that cause apoptosis (cell death).

Answer 26

A cell might first lose activity of a cell cycle inhibitor, an event that would make the cell’s descendants divide a little more rapidly. It’s unlikely that they would be cancerous, but they might form a benign tumour a mass of cells that divides too much. Over time, a mutation might take place in one of the descendant cells, causing increased activity of a positive cell cycle regulator. The mutation might not cause cancer by itself either, but the offspring of this cell would divide even faster, creating a larger pool of cells in which a third mutation could take place. Eventually, one cell might gain enough mutations to take on the characteristics of a cancer cell and give rise to a malignant tumour, a group of cells that divide excessively and can invade other tissues.

Answer 27

* PIK3CA mutations most commonly occur concomitantly with loss of adenomatous polyposis coli (APC). APC has many functions, the most prominent is its capacity to regulate beta-catenin-mediated gene transcription in response to Wnt signalling. Unbound ß-catenin binds to Tcf/Lef gene, which transcribes for Cyclin B & D. Loss of APC leads to deregulated beta-catenin and hyperproliferative epithelium. * Increased genetic instability, and loss of P53 (protein involved in G1 checkpoint preventing damaged DNA from replicating) leads to early adenoma. p53 is the gene most commonly mutated in human cancers, and cancer cells without p53 mutations likely inactivate p53 through other mechanisms * The Rb protein is implicated in the G1 checkpoint; when Rb is permanently in on mode, G1 phase of cell cycle is continually driven – point of no return. * HER-2 receptors are upregulated in tumour cells; hyperactivation of this signalling pathway & abnormal cell proliferation is observed * K-Ras mutation/ activation disrupts negative signalling pathway causing unregulated proliferation into intermediate adenoma (MAPK pathway).

Answer 28

• Sustaining proliferation signalling o G1 phase is implicated, Rb protein function is lost. • Activating invasion and metastasis Cancer cells gain the ability to migrate to other parts of the body. • Inducing Angiogenesis o promoting growth of new blood vessels to give tumour cells a source of oxygen and nutrients • Resisting cell death via lack of apoptosis o Cancer cells also fail to undergo programmed cell death, or apoptosis, under conditions when normal cells would (e.g., due to DNA damage) Emerging hallmarks • Evading growth suppressors o Secretion of immunosuppressive factors enables cancers to avoid destruction from the immune system. • Enabling Replicative immortality o Metabolic changes that support increased cell growth and division. Enabling characteristics • Promoting inflammation • Genome instability allows mutations to accumulate more rapidly

Answer 29

34% of patients diagnosed with breast cancer have chemotherapy as part of their primary cancer treatment.

Answer 30

The risk of recurrence can be reduced using adjuvant chemotherapy. • Adjuvant = after primary surgery • Neo-adjuvant = before surgery – reduces invasive surgery o Locally advanced tumours o Inflammatory tumours o For larger tumours or those with large amounts of nodal involvement or inflammatory component, neoadjuvant chemotherapy may be used to shrink the tumour before surgery to improve the outcome and preserve remnant breast tissue Although chemotherapy comprises part of a successful regimen for treating breast cancer, as many as 50% of patients fail to benefit due to the development of intrinsic and acquired multiple drug resistance Risk factors associated with onset of a resistant phenotype: genetic predisposition such as mutations in a and b tubulins, and BRCA1/2; induction of expression of multi-drug resistance (MDR) proteins; alterations in spindle assembly checkpoints,cell cycle proteins and apoptosis

Answer 31

Disrupt M phase of cell cycle, leading to cell arrest.

Answer 32

Taxanes (e.g. Paclitaxel) Other taxanes include Docetaxel and Carbazitaxel. Paclitaxel is extracted from the bark of T. brevifolia (Pacific Yew); 12 slow-growing trees are required for the treatment of 1 patient. Paclitaxel is a microtubule stabiliser. It acts during the telophase of M phase, binding to the β subunit of tubulin – the building block of microtubules. The resulting microtubule/paclitaxel complex does not have the ability to disassemble, blocking progression of mitosis and causing prolonged activation of the mitotic checkpoint. This triggers apoptosis or reversion to the G0-phase of the cell cycle without cell division. Paclitaxel does not meet the requirements of good drug-likeness (RMM = 50326.5; 15 H-bond acceptors). It is Class IV (poorly permeable, poorly soluble) of the Biopharmaceutical Classification System, so is not ideal for oral delivery.

Answer 33

* Paclitaxel is given via IV route * Formulation with cremophor (polyoxyl castor oil) improves its water solubility, however cremophor has the potential to cause severe allergic reactions, so pre-administration of steroids and antihistamines is recommended. In addition, cremophor can form micelles in plasma, trapping paclitaxel and preventing distribution to tumour cells. * A new approach at Paclitaxel formulation sees paclitaxel complexed with albumin to create a nanoparticle colloidal system. This solubilises paclitaxel which accumulates in tumour beds. No cremophor is used, avoiding issues related to toxicity.

Answer 34

Taxane therapy may cause peripheral neuropathy (numbness, tingling, paraesthesia, and a burning pain in a stocking-glove distribution). This is related to effects on microtubule function in nerve cells and other healthy tissue. Stress hormones were shown to arrest cells in the G0/G1 phase, which would serve to substantiate the decrease in paclitaxel efficacy, which targets cells in the S phase.

Answer 35

Act during the metaphase, inhibiting microtubule assembly & causing cell arrest (microtubule destabilisers).

Answer 36

Cyclophosphamide • Prodrug, converted to phosphoramide mustard • Targets S phase • Cross-links guanine bases by binding alkyl groups • DNA strands are unable to uncoil, so cells can no longer perform mitosis • Also adds methyl/ other alkyl groups onto other molecules, causing a miscoding of DNA and cell apoptosis Mechanisms of resistance: • Increased ability to repair DNA defects • Decreased cellular permeability to the drug • Increased glutathione synthesis • Inactivation of alkylating agents through conjugation reaction

Answer 37

Doxorubicin • Forms complexes with DNA by intercalation between base pairs • Inhibits topoisomerase II activity, preventing the resealing of DNA strands & inhibiting DNA replication • May also inhibit polymerase activity, affect regulation of gene expression, and produce ROS, causing free radical damage to DNA and triggering apoptosis Epirubicin • Most active during S phase • Forms complexes with DNA by intercalation between base pairs • Inhibits topoisomerase II activity, preventing the resealing of DNA strands & inhibiting DNA replication • Also inhibits nucleic acid & protein synthesis

Answer 38

Thymidylate synthase & dihydrofolate reductase enzymes are involved in the production of thymine (a DNA base); if these enzymes are disrupted, pyrimidine synthesis will cease, and as a result, so will DNA synthesis.

Answer 39

* Bio-transformed to ribosyl- and deoxyribosyl- derivatives * Targets S phase * 5-fluoro-2'-deoxyuridine 5'-phosphate (FdUMP) inhibits thymidylate synthase, therefore inhibits thymidine synthesis, preventing DNA synthesis * 5-fluorouridine triphosphate is incorporated into RNA, interfering with RNA function

Answer 40

• Targets S phase • Inhibits dihydrofolate reductase, preventing DNA synthesis Mechanisms of resistance: • Decreased drug transport into the cell • Altered dihydrofolate reductase enzyme with a lower affinity for methotrexate • Quantitative increase in dihydrofolate reductase enzyme concentration in the cell (gene amplification, increased message)

Answer 41

Top 1 cleaves one strand of DNA and relaxes DNA coil during replication Top 2 cleaves two strands of DNA and relaxes DNA supercoil during replication

Answer 42

* Targets S phase * Interferes with Top 1 activity, preventing re-ligation of single strand breaks causing lethal double-stranded breaks in DNA & apoptosis

Answer 43

* Targets S phase * Interferes with Top 2 activity, inhibiting DNA re-ligation. This causes critical errors in DNA synthesis at the pre-mitotic stage of cell division, leading to apoptosis

Answer 44

Protein kinases carry out post-translational changes to proteins (e.g. serine, threonine, tyrosine or histidine amino acid residues), which affects their reactivity and properties. Phosphorylation is the transfer of a phosphate group from ATP to amino acid residue on protein) gives structural and/or conformational changes to the protein, activating or deactivating it. ``` Protein kinases are involved in cellular function; they are very important in cell signalling and division. Uncontrolled activity leads to uncontrolled cell growth and division. Therefore, in cancer, proteins kinases are targets. Tyrosine kinases are a class of protein kinase, where tyrosine is the phosphorylation site. There are receptor and cytoplasmic tyrosine kinases. ```

Answer 45

EGFR are a family of 4 receptor tyrosine kinases: EFGR (ErbB-1, ErbB-2, ErbB-3, ErbB-4) and HER-1, HER-2, HER-3, HER-4. They have extracellular receptor, transmembrane-spanning domain, kinase domain & ATP-binding domain.

Answer 46

It is a recombinant, humanised Ig1 mAb against the EGFR, HER-2. • Trastuzumab binds to the extracellular ligand-binding domain and blocks the cleavage of the extracellular domain of HER-2. This prevents the phosphorylation of p95, which is used in the signal transduction pathways o Inhibition of MAPK and PI3K pathways lead to an increase in cell cycle arrest, and the suppression of cell growth and proliferation. • Trastuzumab also mediates the activation of antibody-dependent cell-mediated cytotoxicity (ADCC) by attracting the immune cells, such as natural killer (NK) cells, to tumour sites that overexpress HER-2. • Disrupts downstream activity and reduces cell growth and division Trastuzumab must be given via SC injection. Although there are issues associated with SC injection (patient training required, painful at site of injection), it gives good absorption, has a rapid onset of action & is useful if the patient is vomiting or unresponsive. Trastuzumab halves the risk of relapse (hazard ratio 0.54) but is expensive (£25,000 per patient per year).

Answer 47

Imatinib • Binds to the ATP-binding site of the kinase, intracellularly, interfering with phosphorylation of epidermal growth factor receptor (EGFR), and ERBB2 • Disrupts downstream activity and reduces cell growth and division Imatinib meets the requirements of good drug-likeness; it is less than 500 Da, Lop P is < 5, 2 H-bond donors & 6 H-bond acceptors. It is Class I (very permeable, very soluble) of the Biopharmaceutical Classification System, so is ideal for oral delivery.

Answer 48

Lapatinib is an inhibitor of the intracellular tyrosine kinase domains of both HER2 and EGFR receptors. It is useful in HER-2 positive BRCA. Everolimus is an mTOR inhibitor; it reduces the activity of effectors downstream, which leads to a blockage in the progression of cells from G1 into S phase, and subsequently inducing cell growth arrest and apoptosis. It is useful in post-menopausal women with ER positive, HER2 negative locally advanced or secondary breast cancer whose cancer has progressed or recurred when hormone therapy.

Answer 49

Oestrogen receptor positive breast cancer cells require oestrogens to proliferate and metastasise. Oestrogen penetrates breast cancers and activates ER receptors, promoting growth.

Answer 50

1. Tamoxifen 2. Goserelin (GnRH analog) 3. Aromatase Inhibitors

Answer 51

1. Aromatase Inhibitors 2. Tamoxifen (non-steroidal Antioestrogen) 3. Fulvestrant (steroidal Antioestrogen)

Answer 52

Cholesterol –> progesterone –> androstenedione –> estrone/ testosterone –> oestradiol The source of oestrogens depends on whether the patient is premenopausal or post-menopausal.

Answer 53

Most oestrogens are made in ovaries, often by testosterone which is converted in oestradiol (E2). Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH stimulates ovarian release of oestrogen.

Answer 54

Most oestrogens are made outside ovaries; adipose tissue is major source. Androstenedione produces estrone (E1). If a post-menopausal woman with ER+ BRCA, their prognosis is worse because more E1 is produced from adipose. E1 is required for tumour growth & proliferation.

Answer 55

GnRH is responsible for the release of FSH, which is responsible for the ovarian release of oestrogen (E2). Goserelin is a GnRH analogue, acting as a potent inhibitor of GnRH secretion. This therefore decreases E2 levels to levels similar to a postmenopausal state (when the medication is stopped, hormone levels return to normal).

Answer 56

Aromatase enzymes convert androgens into oestrogens (E1); inhibitors of aromatase therefore block synthesis of oestrogen. An example of first-generation aromatise inhibitor is Aminoglutethimide. It blocked all hormone synthesis (cortisol etc) so supplements were needed. Anastrozole (non-steroidal) & Exemestane (steroidal) are third-generation aromatase inhibitors more specific to treat oestrogen dependent breast cancer.

Answer 57

There are a number of oestrogen receptors; are similar to steroidal receptors – intracellular & affect gene transcription. ER-α and ER-ß are oestrogen receptors. ER-α is dominant in the vagina, breast, bone, hypothalamus and blood vessels; ER-ß is dominant in ovaries in females. ER0ß is slightly longer with a number of domains. The C region binds to DNA & the hinge region is where oestrogen binds. When oestrogen binds to ER, the receptors dimerise: ER-α with another ER-α or ER-ß with another ER-ß = homodimers; ER-α with ER-ß – heterodimers.

Answer 58

Oestradiol (E2) binds to both receptors with equal affinity. Circulating E2 enters the cell and reaches ER receptor. Heat shock protein 90 (HSP90) is bound to ER, so E2 dissociates HSP90 from ER. E2 then binds to receptors, which dimerise. Once dimerised, ER enters nucleus. Depending on the cell type, ER binds directly to DNA and affects gene transcription or binds indirectly to DNA (by binding to a transcription factor). There are also extranuclear receptors; G-coupled protein receptor (GPR30 or GPER - oestradiol) sit on membrane, coupled to the bottom by lipid tag. The secondary messenger system is cAMP, which can cause gene transcription when G protein coupled receptor is activated. Non-genomic oestrogenic effects don’t involve DNA transcription; they cause direct physiological effects. Oestrogen receptors can also activate without oestrogen; GF signalling leads to activation of ER via kinase phosphorylation. ER activation causes gene transcription.

Answer 59

A prodrug that requires bioactivation by cytochrome P450 enzymes CYP2D6 and 3A4 to generate the active metabolite, endoxifen. It is a selective oestrogen receptor modulators (SERMs); it acts as a competitive antagonist of oestrogen at ER-α, in the breast. It causes a conformational change in the receptor, modulating the expression of oestrogen-dependent genes. The prolonged binding of tamoxifen results in reduced DNA polymerase activity, impaired thymidine utilization, blockade of oestradiol uptake, and decreased oestrogen response. It is also a partial agonist at other oestrogen receptors, minimising the potential effects of oestrogen deprivation. Tamoxifen is not cytotoxic and does not cause a loss of bone marrow. Ten years of adjuvant treatment with tamoxifen provided women with estrogen receptor-positive breast cancer greater protection against late recurrence and death from breast cancer compared with the current standard of five years of tamoxifen, according to a new study.

Answer 60

Fulvestrant is a steroidal antioestrogen, used in post-menopausal women with disease progression following antioestrogen therapy (Tamoxifen). It competitively & reversibly binds to ER, downregulates ER so that oestrogen is no longer able to bind to these receptors and degrading the ER. This inhibits the growth of the tumour, as it is not able to utilise oestrogen.

Answer 61

T cells are removed from a patient, genetically modified or treated with chemicals to enhance their activity, and then re-introduced into the patient with the goal of improving the immune system’s anti-cancer response.

Answer 62

Stimulate the production of blood cells. They do not directly affect tumours, but through their role in stimulating blood cells, they can be helpful in supporting the person’s immune system during cancer treatment, since chemotherapy and radiation therapy can affect blood cells, putting the patient at risk for developing infections, anaemia, and bleeding problems.

Answer 63

Vaccines constitute an active and specific immunotherapy designed to stimulate the anti-tumour immune response by presenting tumour-associated antigens (TAAs) expressed on normal tissues that are overexpressed on tumour cells. Many TAAs (E.g. MUC1 and HER-2) have been identified and been shown to be specifically recognized by T cells. Induction of strong immunity by cancer vaccines is expected to lead to the establishment of immunological memory, thereby preventing tumour recurrence

Answer 64

Monoclonal antibodies are laboratory-produced substances that can locate and bind to certain proteins. They do this by reacting against tumour-associated proteins on the surface of certain cells. These antibodies can be used to see where the tumour is in the body (detection), or as therapy to deliver drugs, toxins, or radioactive material directly to a tumour. Monoclonal antibodies can be given to target particular molecules on the cell surface. E.g. rituximab to target lymphoma cells and Herceptin to target cells, including breast cancer cells.

Answer 65

Dendritic cell therapy provokes anti-tumour responses by causing dendritic cells to present tumour antigens. Dendritic cells present antigens to lymphocytes, which activates them, priming them to kill other cells that present the antigen. In cancer treatment they aid cancer antigen targeting.

Answer 66

Tumours often down-regulate immune function by expressing PD-L1, a ligand for PD-1 (programmed cell death-1 inhibitory receptor). Pembrolizumab is a monoclonal antibody against PD-1; the binding of pembrolizumab to PD-1 prevents the suppression of immune anti-tumour response.

Answer 67

A range of anti-cancer drugs are chosen. They should act at different stages of the cell cycle, with different mechanisms of action. This helps maximise cytotoxic effect and minimise resistance.

Answer 68

It is important that anticancer drugs are not all given at the same time; there are interactions and conflicting effects: • Anthracyclines have a radio-sensitising effect, and should not be given at the same time as radiotherapy • Trastuzumab increases cardiotoxicity of anthracyclines • Anthracyclines & Antimitotic agents cause myelosuppression (bone marrow), increasing risk of infection • Endocrine (hormone) therapy inhbitis the cell cycle; chemotherapies target different phases of the cell cycle so will have no effect when given with hormone therapy The regime is based on a 21-day cycle, and the anti-cancer drugs are given as follows:

Answer 69

Order of administration Anti-cancer agent Dose Regime 1 5-fluorouracil (antimetabolite) 500 mg/m2 ¬IV bolus Day 1 of 21 for 3 cycles (once every 3 weeks, over 9-week period) Epirubicin (anthracycline) 100 mg/ m2 IV bolus Cyclophosphamide (alkylating agent) 500 mg/m2 IV bolus 2 Docetaxel (antimitotic) 100 mg/m2 IV infusion over 1 hour Day 1 of 21 for 3 cycles (once every 3 weeks, over 9-week period) 3 Trastuzumab (biologic against HER-2 receptor) 600mg SC over 5 mins Day 1 of 21 for 18 cycles (once every 3 weeks, over 54-week period)

Answer 70

Toxicity is dose-related, and primarily effects rapidly dividing cells (blood-forming cells in the bone marrow, hair follicles & cells in the mouth, digestive tract, and reproductive system).

Answer 71

Chemotherapy-induced-nausea-and-vomiting (CINV) are common side-effects of many cytotoxic drugs. CINV may cause considerable distress, leading in some cases to refusal to undergo further treatment, and can also result in serious metabolic disturbances. • Anticipatory (occurring prior to treatment) o Lorazepam (BDZ) relieves anxiety associated with treatment • Acute (occurring within 24 hours of treatment) o Granisetron (5HT3 antagonist) o Metoclopramide (D antagonist) • Delayed (between 24-72 hours post chemotherapy) o Dexamethasone (corticosteroid) o Metoclopramide (D antagonist) o Netupitant (NK1 antagonist) – very expensive so only given in cases of high emetogenic potential • Refractory - over 72 hours following chemotherapy

Answer 72

Epirubicin Cyclophosphamide Docetaxel 5-FU

Answer 73

Epirubicin Cyclophosphamide 5-FU Trastuzumab

Answer 74

Epirubicin (H) Cyclophosphamide (M) Docetaxel/5-FU/Tras (L)

Answer 75

Epirubicin 69-95% Cyclophosphamide 40-60% Docetaxel 80% 5FU

Answer 76

Docetaxel 42-70%

Answer 77

Epirubicin ++

Answer 78

Docetaxel | Trastuzumab

Answer 79

* Fatigue * Hair loss * Easy bruising and bleeding * Infection * Anaemia (low red blood cell counts) * Nausea and vomiting * Appetite changes * Constipation * Diarrhoea * Mouth, tongue, and throat problems such as sores and pain with swallowing * Nerve and muscle problems such as numbness, tingling, and pain * Skin and nail changes such as dry skin and colour change * Urine and bladder changes and kidney problems * Weight changes * Chemo brain, which can affect concentration and focus * Mood changes * Changes in libido and sexual function * Fertility problems

Answer 80

* Non-specific distribution of drug throughout body * Lack of drug selectivity for a particular pathological site * Large total dose of drug required but low dose at site required * Non-specific toxicity and other adverse effects

Answer 81

Drug targeting is the ability of the drug to accumulate in the target organ or tissue selectively independent of the site or method of administration.

Answer 82

Nanoscale drug delivery systems can increase the concentration of drug at site of action through passive or active targeting. In addition, they can decrease drug concentration in normal (non-diseased tissue) to reduce toxic side effects and they improve pharmaco-kinetic/dynamic profiles. To achieve this, minimum amounts of drug should be released during transit, and as much as possible should be released at targeted site.

Answer 83

• Nanoparticles o Solid, spherical ~100 nm in size with drug in polymer matrix • Nano-capsules o Drug entrapped in a cavity surrounded by a polymer membrane • Polymeric micelles o Spheroidal structure with hydrophobic core which increases solubility of poorly-water soluble drugs, and hydrophilic corona which allows a long circulation time and prevents interactions between core and blood. Dynamic structures ~50 nm. • Liposomes o Closed spherical vesicles formed by one or more phospholipid bilayers around an aqueous core in which drug can be entrapped.

Answer 84

As with any foreign particle that enters the body, liposomes encounter multiple defence systems aimed at recognition, neutralization, and elimination of invading substances. The Reticuloendothelial system (RES) is an important component of the immune system. This comprises phagocyte cells found in various organs of the human body. They are located in reticular connective tissues. Upon leaving the circulatory system, phagocytes become macrophages. Macrophages will readily take up and phagocytose liposomes.

Answer 85

Doxorubicin can be given using stealth liposomes (>90% of doxorubicin is encapsulated). Stealth liposomes are protected from detection by the mononuclear phagocyte system because they are coated using surface-bound methoxy PEG. This increases blood circulation time and increases the chance of being taken up by tumour cells. In addition, doxorubicin is less cardiotoxic, myelotoxic and nephrotoxic in this formulation because distribution is altered.

Answer 86

Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. This occurs when a tumour exceeds 2mm. Defective blood vessels have sac-like formations and fenestrations, which have enhanced permeability & retention. There is enhanced permeability for drugs/carriers to move from microcapillaries to interstitium surrounding tumour cells and a lack of lack of lymphatic drainage, so drugs will be retained in the tumour interstitium. Drugs should be >10 nm to avoid filtration by kidneys and <100 nm to avoid capture by liver and should be neutral or anionic to avoid renal elimination.

Answer 87

A ligand is attached at surface of a nanocarrier for binding to appropriate receptors at target site. The ligand may allow the drug to attach to the surface of cell or internalise for intracellular drug release. This formulation is known as Liganded PEGylated Nanoparticle.

Answer 88

Aims of active targeting of cancer cells are: • To improve cellular uptake of therapeutic macromolecular drugs • To target surface receptor over-expressed by cancer cells only • To target receptors that are likely to be internalised (such as EGFR) Tumour endothelial cells (not cancer cells) can be targeted too; the aim is to destroy angiogenic blood vessels and kill tumour cells by depriving them of oxygen and nutrients.

Answer 89

Isobars are atoms of different elements having the same mass number (e.g. 6C14, 7N14, 8O14). Isotones are atoms of different elements having the same number of neutrons (e.g. 14Si30, 15P31).

Answer 90

``` A = atomic mass (p+n) Z = proton number (also electron number) Sy = element ```

Answer 91

Nuclear instability is caused by the size imbalance of proton: neutron ratio. Two different isotopes of the same element will have different tendencies to undergo nuclear decay; carbon-14 (6 protons + 8 neutrons) is more likely to decay than carbon-12 (6 protons + 6 neutrons).

Answer 92

The strength of emission is measured in electron volts (eV), where the lethal dose is > 3 MeV • Α decay (fusion) o A nucleus breaks down, and a helium atom is released o E.g. Ra → Rn + He2+ (helium atom – 2 protons & 2 neutrons) o 1 α gives 10,000 atomic ionisations o Most damaging to tissues, but least penetrating (µm) – dangerous when inside the body • Beta decay o Positron (anti-electron) – ß+ decay  A neutron suddenly changes into a proton, causing the release of a positron – an electron with a positive charge o ß-particle (electron) – ß- decay  A neutron suddenly changes into a proton, causing the release of an electron & neutrino  E.g. K  Ca + e- + v o 1 beta gives 100 atomic ionisations o Damaging to tissues and penetrating (cm) – dangerous when outside the body • Gamma decay o The nucleus rearranges to a lower energy state, a photon (gamma ray) is released o 1 gamma gives 1 atomic ionisations o Very high energy & highly penetrating, causing DNA damage.

Answer 93

Discovered by Marie Curie: Uranium – (238@92) U is the most abundant isotope (99.27%) and is a natural α emitter Radium – 223Ra is a radiopharmaceutical produced from the decay of 235U Polonium – 210Po is a powerful α emitter, 1 million times more toxic than cyanide

Answer 94

``` Element Half-life Use Gallium , 68Ga 68 min Imaging Rubidium, 81Rb 4.7 h Molybdenum, 99Mo 66 h Moly-Cow (used to extract 99mTc) Polonium, 210Po 180 day Germanium, 68Ge 280 day Cobalt, 60Co 5 years Sterilisation ```

Answer 95

Most radiotherapy treatment is given by External Beam Radiation Therapy (EBRT). Tumours with a diameter of ≥2 cm can be treated using EBRT. 63% of patients diagnosed with breast cancer have radiotherapy as part of their primary cancer treatment. RTX is recommended after a lumpectomy. The survival rate of BRCA is increased by 32-67% with the use of radiotherapy.

Answer 96

``` Radiotherapy involves daily treatments for 6/7 days over 6 weeks. Dosing regimens (Gy/hour): • Low dose rate (LDR): <2 • Moderate dose rate (MDR): 2-12 • High dose rate (HDR): >12 ```

Answer 97

• IMRT – Intensity modulated radiotherapy (IMRT) • IBRT – Internal Beam Radiotherapy (internal mammary radiotherapy) o the insertion of radioactive implants (platinum, iridium, indium and palladium) directly into tissue o Often used for large and capsulated soft tissue tumours • IORT – intraoperative radiotherapy

Answer 98

Radiolysis of water produces hydrogen and hydroxy ions and hydrogen and hydroxy free radicals: water: H+ + HO- + H• + HO•. Additional contact with nearby oxygen creates super-oxides, which cause damage to the cell (indirect DNA damage). These destroy DNA by breaking double strands, leading to cell death. If a tumour is anorexic, it is deprived of oxygen due to rapid outgrowth of blood supply, therefore fewer superoxide are produced; solid tumours are very anorexic and are radio-resistant above 0.5cm3. Fractionation is where the total dose of radiation is divided into several, smaller doses over a period of several days. This reduces the toxic effects on health cells.

Answer 99

• Repair o Although non-cancerous cells may be affected, their ability to heal double-strand breaks is better than cancer cells o Fractionation allows normal cells to repair • Repopulation o Tumour cells can repopulate when incompletely damaged o Each fraction (dose of radiation) must cause more damage than the cells ability to repopulate o Fractionation allows normal cells to repopulate • Re-assortment o Each fraction allows re-assortment of tumour cells to be in the M-phase o More considerable DNA damage is caused • Reoxygenation o Most DNA damage is indirect (caused by super-oxides due to free radical contact with oxygen) o Fractionation causes oxygen-rich tumour cells to die first, and previously hypoxic tumour cells to become oxygenated o Cells are more susceptible to radiation in next fraction.

Answer 100

Exposure to radiation has many effects, including fatigue, fever, vomiting & nausea (from first exposure), white blood cell damage (after 7 days), hair loss (after 12 days). Other effects include abdominal pain, palpitations, promotion of cancer, and organ damage.

Answer 101

A radionuclide generator is a source of radionuclides for radiopharmaceuticals. The most commonly used generator in Nuclear Medicine is the is (technetium-99metastable/Molybdenum-99) 99Mo/99mTc generator. It has a short half-life (6 hours), can be easily manufactured. Technetium-99m is used as a radioactive tracer and can be detected in the body by medical equipment (gamma cameras). It is well suited to the role, because it emits readily detectable gamma rays. When complexed to methylenediorthophophonate (MDP), Tc99m is incorporated in broken bones; a radioactive tracer may view this radioactive blood pooling, indicating a broken bone. Soft tissue doesn’t uptake Tc99m Tc-sulphur colloid is used in BRCA sentinel lymph node treatment.

Answer 102

Ultrasound waves reach an object or surface with a different texture and a wave is reflected back. Ultrasound waves are not ionising, but do not penetrate gas or bone, so gaseous areas of the body (lung, bowel) and any bone structures cannot be observed using this method. Solid organs, muscles and tendons may be observed and they are utilised in foetal examinations.

Answer 103

X-rays blacken photographic film; more dense structures (bone) appear white and less dense structures (soft-tissue, fat) appear black. X-rays are used to confirm bone fractures or breaks. It is a non-invasive, ionising imaging technique. Hydroxyapatite is what bone is made from- phosphate salt of calcium.

Answer 104

CT scans show a slice, or cross-section, of the body. X-ray images result from attenuation of the X-rays by the material through which they pass. Attenuation is the removal of X-rays from a beam, by absorbing or scattering them; the greater the density of a material, the greater it absorbs/scatters X-rays. The image shows your bones, organs, and soft tissues more clearly than standard x-rays. X-ray computer tomography uses massive doses of ionising radiation; effective dose of head CT is 100 times greater, chest CT is 300 times greater and abdominal CT is 400 times greater.

Answer 105

Ionising radiation (lower-energy X-Rays) is used as a complement to ultrasound, ductography, positron emission mammography (PEM), and magnetic resonance imaging (MRI), to give an X-ray image of breast tissue. Parallel plates are used to compress breast tissue to reduce exposure and scatter X-rays.

Answer 106

MRIs produce far more detailed images of the structure of a patient’s blood vessels, nerves, bones, and organ. An MRI takes pictures of places in your body that contain water, and the detail in these images comes from the ways that different tissues interfere with the electromagnetic waves coming from water molecules. Protons are aligned parallel (lower-energy state, preferred) or anti-parallel. A very strong, constant magnetic field forms that remains in place for the duration of the measurement, and this super-strong field makes all the protons try to line up with the poles of the field. The MRI machine intentionally disrupts this field by sending a brief pulse of an additional, weaker electromagnetic field. This weaker pulse points in a different direction than the constant magnetic field, and so it disrupts the protons so that they become misaligned with the constant field. Because different places in the body contain different amounts of water, MRI detects the electromagnetic fields of the atoms in water molecules and uses this to determine differences in the density and shape of tissues throughout the body.

Answer 107

A positron (ß+ decay) travels a short distance before colliding with an electron of a nearby atom leading to annihilation, where 2 gamma rays (photons) are produced, emitted at 180º to one another. The photons are detected by an external gamma camera. 18F-FDG (18F-fluorodeoxyglucose) is the most commonly used PET radiopharmaceutical. It has a half-life of 110 minutes, allowing it to be transported around the body. FDG is used to measure the rate of glucose metabolism useful for cardiac studies, tumour localisation and quantitation, differentiating between benign and malignant tumours, and monitoring tumour therapy.

Answer 108

Combination of PET (metabolic imaging) with CT (anatomical imaging) to produce a single image detailing anatomic structure and metabolic function to accurately observe abnormalities.

Answer 109

Bandages, scalpels, stents, needles & cannulas can be sterilised using gamma rays.

Answer 110

``` Side effects of treatment Hair loss Fatigue Changes to appearance: reconstruction? When?? Clothing??? Lymphoedema Menopausal symptoms Fertility issues ``` Changes to body Ongoing hot flushes & mood swings Vaginal dryness (because of lower oestrogen levels) Sexuality: period of adjustment – not talked about as much as other side effects but can be just as debilitating Anxiety Depression 25% women diagnosed with breast cancer suffer significantly - require medication /CBT or other structured psychological help Effects on the heart, lungs and bone health due to: - Chemotherapy/Hormonal therapy - Radiotherapy - Early menopause Weight gain: less active, onset of menopause, steroids whilst having chemo

Answer 111

Comparing the costs and benefits of interventions and making choices is the basis of health economics. Decision makers need to consider the cost and the benefit of new interventions; in the UK, the cost-effectiveness is preferred. Interventions are compared with one another or the SOC, and an incremental cost for the benefit is reported.

Answer 112

EQ-5D questionnaire includes mobility, self-care, effect (improvement, worsening) on activities, pain/ discomfort experienced, anxiety/ depression. The EQ-5D does not include social contact or employment, and certain diseases influence EQ5D more (physical conditions may influence the score more than mental conditions). The EQ-5D can be used to calculate utility and compare between therapies; a quality-adjusted life year (QALY) is often used – one QALY is equal to 1 year of life in perfect health. e.g. Drug A costs £20,000 per 1 QALY; Drug B costs £60,000 per 1 QALY – Drug A would be preferred. "ICER= " "Cost A-Cost B" /"Benefit A-Benefit B" A drug is deemed cost-effective if it is £20-30,000 ICER per QALY; end of life treatment (extends life beyond three months) is cost effective if £50,000 ICER per QALY.

Answer 113

If a drug falls in quadrant 1, it is less effective and more expensive, so will be rejected. If a drug falls in quadrant 4, it is more effective and less expensive, so will be accepted. If a drug falls into quadrants 1 or 3, an ICER must be performed to compare the cost-effectiveness. Decision analysis models are used to simulate costs & consequences of different care pathways. The probability of a patient following a pathway is assessed and the pathway costs and benefits assigned; decision trees may be used for simple diseases in acute settings, but for complex diseases, there are too many options for them to be viable.

Answer 114

1- less effective, more costly (dominated) 2- more effective, more costly 3- less effective, less costly 4- more effective and less costly (dominant)

Answer 115

The probability of length of time spent in different health states is calculated, developing QALY based on the cycling. This gives a better indication on cost-effective scale. It is useful for cancer, as it accounts for progression states.

Answer 116

SA is essentially the study of how changes in model inputs (quantities, prices, life years, probabilities) affect model outputs (average or expected costs, average or expected benefits, average or expected ICER or Net Monetary Benefit). There are two types of sensitivity analyses: 1. Deterministic: Values for one or more parameters are chosen, and the rest are kept constant 2. Probabilistic: Parameters and probability distribution are assigned, and simulations are used to compute new ICERs

Answer 117

To gain marketing authorisation, there is a high cost for pharmaceutical companies, so they aim to make some of this back. Most incurable cancers are treated with each approved agent (sequentially or in combination), creating a virtual monopoly because the use of one drug does not automatically mean that the others are no longer needed. Generics are seen as sub-standard to new therapies and are therefore not used. In addition, cancer is seen as a more serious disease, so there is increased willingness to pay a higher price.

Answer 118

Established in 2010, the aim was to give cancer patents access to non-NICE approved drugs. Initially set at £50 million, the fund is now £280 million. It was put into place temporarily as a new method of cost effectiveness analysis was developed – value-based pricing (VBP). In terms of pharmacoeconomics, the cancer drugs fund is disastrous; there has been an exponential rise in cost. The CDF may undermine the underlying NICE/NHS principle that all lives are of equal value. The new CDF (from 2016) is part of NICE and aims to review all new cancer drugs within 90 days of license for use in England, and 1 of the following 3 decisions will be made regarding the use: • Yes - the drug should be routinely available on the NHS • No - the drug should not be routinely available on the NHS • Maybe - the drug can be made available via the Cancer Drugs Fund, to ensure efficacy before allowing routine availability

breast cancer Flashcards

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