Week 6 Flashcards
Why is an understanding of cancer pathology important
Explains how cancers present clinically:
-rectal bleeding
-cutaneous mass
-jaundice
-haemoptysis, respiratory distress
Histopathological assessment important for:
-diagnosis: tissue confirmation required to diagnose cancer, tissue for subtyping the cancer, need to understand terms used in pathology reports
-prognosis: tumour grading and staging
-treatment: eg surgical resection, chemotherapy, radiotherapy
-additionally ancillary test eg molecular testing for prediction of chemo/immunotherapy
Neoplasia
A neoplasm is a mass of cell that:
-have undergone an irreversible change from normality and
-proliferate in an uncoordinated manner
-are partially or completely independent of the factors which control normal cell growth
Neoplastic growth persists even if the initiating stimulus is withdrawn
Neoplasm literally means “new growth”: a commonly used synonym for neoplasm is tumour (swelling)
Definition of cancer
A malignant neoplasm
Classifications of neoplasms
Behaviour - benign or malignant
Histiogenesis- tissue of origin/differentiation
Histological- sub typing within a tissue
Functional- hormonal secretion
Behaviour and histiogenesis are two most important features used in classifying neoplasms
Benign vs malignant neoplasms
Malignant neoplasms have the capacity for:
-local invasion into surrounding tissue
-spread to distant sites to form secondary deposits (metastases)
—metastasis occurs via two main routes (lymphatic and haematogenous)
The term cancer is used to describe all types of malignant neoplasm
Some neoplasm behave in an “intermediate” manner
-eg basal cell carcinoma of skin - invades local tissues, but doesn’t metastasise)
Liver haemangioma, benign neoplasm- well circumscribed
Neoplasm of vasculature structures of liver- haemangioma
Typical appearance of benign neoplasm: well circumscribed- doesn’t invade locally
Staging of malignant neoplasms
Staging= extent of spread (local or distant)
Numerous staging systems exist
-some are disease/organ specific
-a commonly used generic system is TNM
T=tumour
N=nodes
M=metastasis
Staging has important implications for prognosis and treatment
Neoplasia- tissue of origin
Epithelial
-most malignant neoplasms termed ‘carcinoma’ (eg skin, lung, GIT)
Mesenchymal tissue:
-many benign neoplasms eg soft tissue “lipoma”, muscle “leiomyoma”, blood vessels “haemangioma”
-if malignant termed “sarcoma”
-mesothelium- mesothelioma
Other:
-haemato-lymphoid neoplasms, termed “lymphoma” from lymph nodes or “leukaemia” if involving blood cells
-germ cell neoplasms- teratoma, Seminoma
Differentiation
Differentiation is the degree to which a neoplasm histologically resembles its tissue of origin
Benign neoplasms- always well differentiated (always closely resembles tissues of origin)
Malignant neoplasms- differentiation variable
Grading
Grading is a term used to describe the degree of differentiation
Grade 1- well differentiated
Grade 2- moderately differentiated
Grade 3- poorly differentiated
Grading has implications for prognosis and treatment
-poorly differentiated cancers behave more aggressively
-well differentiated cancers have better prognosis and certain well differentiated cancer eg prostate can be managed conservatively
Some malignant tumours are so poorly differentiated that it’s impossible to determine their histiogenesis. These neoplasms are called anaplastic
Classification of common neoplasms
Epithelium origin:
-squamous— squamous cell papilloma (Benign), squamous cell carcinoma (malignant)
-transitional- transitional cell papilloma (b), transitional cell carcinoma (M)
-glandular- adenoma (B), adenocarcinoma (M)
Mesenchyme:
-fat— lipoma (b), liposarcoma (M)
-fibrous tissue— fibroma (b), fibrosarcoma(m)
-smooth muscle -leiomyoma (b), leiomyosarcoma (m)
-skeletal muscle- rhabdomyoma (b), rhabdomyosarcoma (m)
-cartilage- chondroma (b), chondrosarcoma (m)
-bone- osteoma(b), osteosarcoma (m)
Thyroid carcinoma
Different behaviour according to histological subtype
Papillary: freq 75-85%, lymphatic spread (lymph node metastasis), very good prognosis 5 year survival>95%
Follicular: freq 10-20%, haematogenous spread (bone metastases), good prognosis 5 year survival >80%
Anaplastic: freq 5%, local invasion, poor prognosis (most dead within 1 year)
Classification of neoplasms functional
Classification according to substances produced
-endocrine neoplasms secreting functionally active hormones
-insulinoma= insulin producing pancreatic islet cell neoplasm
-prolactinoma= prolactin producing anterior pituitary neoplasm
Other tumours and tumour like conditions
Teratomas
Embryonic neoplasms
Hamartomas
Teratomas
Neoplasms derived from embryonic germ cells
Have the capacity to form representatives of all 3 germ cell layers (totipotential cells)
Teratomas occur in the following sites:
-ovary- usually benign
-testes- usually malignant
-midline structures (retroperitoneum, mediastinum)-behaviour variable
Embryonic tumours
Arise from neoplastic transformation occurring in the developing organ
Derived from multi-potential embryonic “blast” cells and given the suffix- blastoma
Frequently have divergent differentiation eg epithelial and mesenchymal
Majority present at or soon after birth. Commonest type of neoplasm in childhood
Most are highly malignant (but may respond well to aggressive treatment)
Examples:
-nephroblastoma (Wilma’s tumour)
-hepatoblastoma
Hamartomas
Not genuine neoplasms but tumour like malformations
Many present at birth and stop growing when the host stops growing
Examples: peutz Jeghers polyp, bronchial hamartoma, biliary duct hamartoma
Comparison between benign and malignant neoplasms
Essential differences
Gross appearance
Microscopic features
Growth characteristics
Effects on host
Essential differences between benign and malignant
Invasion: B=no, M=yes
Metastasis: B=no, M=yes
Gross appearance benign vs malignant
Shape: b=well circumscribed, m-irregular
Size: b=generally smaller, m=generally larger
Haemorrhage: b=unusual, m=common
Ulceration: b=unusual, m=common
Necrosis: b=unusual, m=common
Microscopic features benign vs malignant
Nuclear size: b=normal, m=enlarged
Nucleoli: b=small/inconspicuous, m=prominent
Pleomorphism and loss of polarity: b=absent, m=often marked
Mitoses: b=infrequent, m=frequent (may be atypical)
Differentiation: b=good, m=variable
Anaplastic carcinoma
Big nuclei
Prominent nuclei
Several mitoses
Growth characteristics benign vs malignant
Speed: b=slow, m=rapid
Spontaneous arrest: b=common, m=rare
Comparison between benign and malignant neoplasms effects on host
Mechanical pressure: b=yes, m=yes
Invasion: b=no, m=yes may damage vital structures
Metastasis: b=no, m=yes common cause death
Paraneoplastic syndromes : b=no, m=yes (esp lung cancer) neurological, haematological, endocrine, immunological, other
Death: b=very uncommon, m=frequent (if untreated)
Pathology as a clinical discipline
Specimens from living people
Approx 70% of hospital diagnoses based on pathology “tests”
-majority are simple tests (eg blood samples)
-others are more complex and invasive (eg biopsies, surgical resection, specimens, molecular biology tests)
Information also important for prognosis and treatment
Why is an understanding of tumour pathology important
Clinical presentation and natural history
Terms used to classify neoplasms and their clinical relevance
Treatment options
How are neoplasms classified
Behaviour- benign or malignant
Tissue of origin/differentiation
Histological subtypes
Knowledge of gross features helpful in distinction between benign and malignant lumps (clinical examination, radiology)
Benign= smooth, well circumscribed, mobile
Malignant= irregular, poorly defined, may be fixed to adjacent tissues
Fibroadenoma
Commonest benign breast neoplasm
Mostly occurs in young women <30
Smooth well circumscribed lumps, highly mobile on palpation (“breast mice”)
Breast carcinoma
Commonest malignant breast neoplasm
Commonest cause of cancer death in women
Mostly occur in older women (75%>50 years)
Irregular, poorly circumscribed lumps, rarely mobile on palpation (due to invasion of surrounding structures)
In which layer of the colon do majority of neoplasms arise
Mucosa
Colon carcinoma- clinical presentation
Caecum/ascending colon: often polypoid, rarely cause bowel obstruction, insidious presentation- eg anaemia, weight loss
Sigmoid colon: often stenosing, frequently cause bowel obstruction, typically present with alteration in bowel habit
Specimens obtained for pathological assessment
Biopsies:
-endoscopic biopsies (upper and lower GIT, bronchus)
-needle biopsies (radiologically guided)
-punch biopsies (skin)
Cytology specimens (cells-individuals or small groups)
-smears (eg cervical)
-endoscopic brushings
-body fluid (eg sputum, urine, effusion fluids)
-fine needle aspiration specimens
Surgical resection specimens
Frozen section specimens (intraoperative)
Biopsies and cytology specimens
Mainly taken to confirm a diagnosis of malignancy and identify histological type
Information used to plan further treatment
-eg surgical resection versus non surgical approaches
-decisions relating to therapeutic options are frequently made in multidisciplinary team meetings
Limitations of biopsying tumours
Tumour heterogeneity
Targeting the lesion accurately:
-small lesions
-inaccessible (or potentially dangerous sites)
-surrounding stromal reaction (pancreatic cancer)
Cytology specimens
Diagnostic material obtained using less invasive methods
-bladder cancer- urine cytology versus cystoscopy
-fine needles used to aspirate material for cytology are much thinner than those needed to obtain biopsy material
—may provide access to sites not suitable for biopsy (eg pancreas)
Smaller tissue samples provided (individual cells or groups of cells rather than tissue cores)
-interpretation may be more difficult than larger specimens obtained using biopsy)
Surgical resection specimens
Surgical resection is generally indicated to be a definitive (curative) treatment for cancer. In some cases it may be used in a palliative manner
Pathological assessments are used to:
-confirm the diagnosis of malignancy
-determine the aggressiveness of a tumour (histological grade)
-assess the extent of spread (histological stage)
-examine completeness of excision
This information may be used as the basis for determining further treatment (eg adjuvant chemotherapy)
Other pathological assessments can sometimes be used to identify more specific therapeutic options
Tumour resection specimens- macroscopic assessment
Size
Shape (well circumscribed or irregular)
Extent of local spread
Proximity to surgical resection margins
Identification of lymph nodes (important for staging)
Other macroscopic features where relevant (eg colour, haemorrhage, necrosis)
Tumour resection specimens- microscopic assessment
Confirms (or establishes) a diagnosis of cancer
Other features that are assessed microscopically include the following:
-histological type (glandular, squamous)
-degree of differentiation (histological grade)
-frequency of mitoses
-local invasion
—presence: is important in determining a diagnosis of malignancy (eg capsular invasion in follicular carcinoma of the thyroid gland or hepatocellular carcinoma)
—extent is important in staging
Vascular invasion
Examination of lymph nodes (for metastases)
Hepatocellular carcinoma
Well differentiated tumour showing capsular and vascular invasion
Presence of capsular or vascular invasion confirms diagnosis of malignancy
Presence of vascular invasion up stages tumour from T1 to T2
The royal college of pathologists minimum datasets for reporting cancer
Describe core data that should be provided in histopathology reports
Uniform approach to handling resection specimens:
-prognostic information
-accurate data for cancer registration
-feedback on the quality of resection
-selecting patients for adjuvant therapy (including clinical trials)
-auditing effectiveness of pre-operative staging procedures
Histological grading hepatocellular carcinoma
Well differentiated: closely resembles tissue of origin, may also be classified as low grade, grade 1, more favourable outcome
Undifferentiated/anaplastic: Anaplastic= no resemblance to any normal tissues in site of origin, may also be classified as high grade Grade III, poor prognosis
Staging of malignant neoplasms
Staging is a measure of the extent of spread of a tumour most important factor predicting prognosis in most tumours
TNM. T(1-4), N(0-3), M(0-1)
Role of immunohistochemistry and molecular pathology
Immunohistochemistry:
-a method of detecting the presence of specific proteins in cells or tissues, an antibody for each antigen
Molecular pathology: gene mutation analysis; FISH; deletion of specific translocations
-to support the diagnosis (specific translocations in sarcomas (myxoid liposarcomas, synovial sarcoma, Ewing’s tumour)
-to predict response to targeted drugs (KIT in GIST; EGFR2 in breast adenocarcinoma; RAS in colorectal adenocarcinomas)
Immunohistochemistry in tumour pathology
Prognostic markers:
-markers of cell turnover (eg Ki-67 labelling index)
-may be used to determine tumours of low or high metastatic potential
—eg pancreatic endocrine neoplasms (also applies to other endocrine neoplasms)
—most cases well differentiated (low grade) by conventional histological criteria and behaviour difficult to predict
-Ki 67 labelling index <2% low metastatic potential
-Ki 67 labelling index >20% high metastatic potential
Also used to determine prognosis (and sometimes treatment options) in tumours already known to be malignant. Often correlates with other histological features (mitotic activity, degree of differentiation)
Identifying therapeutic options
Expression of specific antigenic markers used to identify tumours that are likely to be amenable to specific therapies targeting the antigens expressed
-breast carcinomas expressing the growth factor HER2 can be treated with herceptin
-breast carcinomas expressing oestrogen receptor may be amenable to hormone therapy
-metastatic colonic (and gastric) adenocarcinomas showing deficient/loss of mismatch repair proteins can be treated with immunotherapy
Role of molecular biology
Diagnostic:
-translocations in sarcomas and lymphomas
-B and T cell clonality
-KIT/PDGFRA gene mutation in GIST
Prognostic:
-1p 19q LOH in gliomas: better prognosis
-mismatch repair protein alterations in colorectal cancer: better prognosis
-immunoscore: prognostic/predictive in colon cancer
-oncotype, prosigna, endopredict in breast cancer
Predictive
predictive tests in molecular biology
Targeted treatments;
-HER2 amplification in breast, oesophageal/gastric and lung cancer
– RAS mutation prior to anti EGFR1 antibody in metastatic colorectal ADC: negative predictive marker
– EGFR1 mutation prior to anti EGFR1 small molecules in NSCLC (tissue or/and plasma)
– KRAS G12C in lung cancer
– KIT/PDGFRA mutation in GIST and melanoma
– BRAF mutation in melanomas and lung cancer prior to targeted therapy
– ALK, ROS1, RET translocation in lung cancer
– MET exon 14 skipping mutation in lung cancer
– NTRK translocation testing in any solid tumour
– PIK3CA mutation in breast carcinoma
– FGFR2 rearrangement and IDH1/2 mutations in cholangiocarcinoma
– MMR testing in upper GI cancer
– PD-L1 expression prior to check point inhibitor therapy: lung, head and neck, melanoma, bladder, breast, oesophageal, gastric, cervical carcinoma
Integrated report including pathology, gene mutations, protein expression profile, chromosomal alterations
Optimal pathology report of a cancer
-histology: nature of tumour and sub typing through immune profile
-immunohistochemistry single test, IVD protocols, quantification on digitalised slides
-DNA analysis in FFPE and plasma single mutation, NGS
-FISH partial automation of interpretation on digitalised slides
Multidisciplinary team meetings
Many important decisions relating to the diagnosis and treatment of malignant neoplasms now take place in the setting of MDT meetings
Core members:
-histopathologists
-radiologists
-surgeons
-oncologists
-other health care professionals (eg specialist nurses)
The presence of recognised MDT meetings and regular attendance by core members is now a requirement in order for a hospital to be recognised as a cancer treatment centre
Regularly monitored by cancer peer review teams
History of leukaemia
Original descriptions by Cragie, Virchow, Bennett 1840
First description of Philadelphia chromosome- 1960
Chronic myeloid leukaemia other landmark discoveries :
-Janet Rowley et al: a new consistent abnormality in chronic myelogenous leukaemia identified by quinacrine fluorescence and giemsa staining
Historical treatment options:
-1964= hydroxyurea
-combination therapy
-1975=bone marrow transplantation
-1983=interferon alpha
-2001= imatinib
CML epidemiology
1-2/100000
Scotland 0.9/100000 (2008)
Increases with age
Virtually none below 8 years old (rare in children)
(Chronic) myeloproliferative diseases
Excess of myeloid cells
Primary polycythaemia- too many red cells
Primary thrombocythaemia- too many platelets
Idiopathic myelofibrosis- too much marrow fibrosis
Chronic myeloid leukaemia CML- too many neutrophils
They’re all related in a way all can transform into something else
Chronic myeloid leukaemia
A type of myeloproliferative disease:
-accumulation of myeloid progenitors
-high white blood cell count
-large spleen
Can transform into acute leukaemia
Previously treated with:
-myelosuppressive therapy (hydroxycarbamide)
-transplantation
Peripheral blood film from patient with CML
Many mature granulocytes
Basophils
Blast cell
The Philadelphia chromosome
Almost every patient with CML will have a Philadelphia chromosome 90%
The Ph chromosome: t(9;22) translocation
CML involves 2 genes
One is BCR lies on C22
Other is ABL lies on C9
You get fusion of part of BCR gene onto next part of the ABL gene
So end up with BCR-ABL fusion gene
ABL is tyrosine kinase- converts ATP to ADP to phosphorylated other proteins
In normal cell ABL will not always be expressed
However by fusing it with BCR it becomes constructively active inside WBC
BCR::ABL fusion gene
Fusion creates new gene and thus new protein
You can see the gene being joined together using FISH- fluorescent in situ hybridisation
You can label the genes by using fluorescent probes
BCR::ABL is found in normal people as well
The Philadelphia chromosome t(9;22) and BCR::ABL
You get various different fusions depending on where they are joined together. Therefore have various different lengths
They’re also associated with slightly different kinds leukaemia
P190BCR-ABL
P210BCR-ABL
P230BCR-ABL
Presentation of CML
Variable
Asymptomatic
Hyperviscosity- from high WBC
Specific symptoms:
-bleeding
-anaemia, tiredness
-infection (recurrent) as WBC may not function properly
Patient with massive splenomegaly in chronic phase chronic myeloid leukaemia
Common symptoms and signs:
-fatigue
-weight loss
-sweating
-haemorrhage- eg easy bruising, discrete ecchymoses
-splenomegaly
Blood values:
-Hb 7.9g/dL (anaemia)
-WBC 467 x10^9/L (very high)
-PIts 600 x10^9/L
Massive splenomegaly: can result in rare symptoms
-splenic infarction
-leucostasis
-gout
-retinal haemorrhages
-priapism
-fever
Diagnosis
Blood count and film
-elevated white cell count
-low platelets and haemoglobin
-film
Biochemistry:
-abnormal liver function can occur
-impaired renal function- raised urate
-raised lactate dehydrogenase LDH
Need to exclude other causes eg bacterial infection, other malignancies
Haematological investigations
Blood counts
Blood film morphology
Bone marrow diagnosis
Cytogenetics
Molecular diagnostics
Haematological diagnosis
Clinical
Blood tests
Blood film morphology
Bone marrow diagnosis
Cytogenetics
Molecular diagnostics (new)- FISH and QPCR
Karyotype analysis: G banding (giemsa)
Here is the 9-22 translocation so we have the diagnosis
We also confirm this via FISH
PCR primers on BCR and ABL read across the breakpoint
PCR is used when you have a bit of DNA that you want to find out it’s sequence eg see if there is BCR-ABL present
The easiest way of doing that is by putting one primer on BCR and one on ABL where you think the break point will be
Heat up DNA, anneal the primer, polymerase it, cool, join together
Every time you double the product see if there’s a BCR-ABL fusion
Real time quantitative PCR
When we treat the patient want to know how much of the gene is around
QPCR tells you how much of the gene is there
Each time the gene is copied the reporter fluorophore is released giving a signal
The intensity of the signal rises exponentially
Compare with a known gene ABL to know how much BCR-ABL you have
Therapy CML
Acute treatment:
-reduce WBC
—hydroxycarbamide weak chemo
—leukapheresis, removes WBCs. For very high WBC and life threatening complications
-prevent hyperuricaemia
—gout
—renal failure
—allopurinal to treat this
—IV fluids stop renal failure
-analgesia for pain relief splenomegaly
Chronic treatment:
-tyrosine kinase inhibitors: imatinib, dasatinib, nilotinib, bosutinib, ponatinib, asciminib
-interferon: 10-20%
-allogenic transplantation
Imatinib is a tyrosine kinase inhibitor TKI
Potent inhibition of Abl-K, c-kit and PDGF-R
Salts are soluble in water
Oral bio available
Not mutagenic
CGP57148: a phenylamino pyrimidine derivative
Imatinib mesylate fits into the ATP binding pocket of BCR-ABL protein
Imatinib inhibits the binding of ATP to ABL tyrosine kinase
Imatinib binds to ATP binding pocket of BCR-ABL prevents phosphorylation of target molecules. So get no downstream signalling and no cell proliferation and survival
Maintains BCR-ABL in inactive state
BCR-ABL is a tyrosine kinase
The kinase domain of abl activates a substrate protein eg PI3kinase by phosphorylation. This activated substrate initiates a signalling cascade leading to cell proliferation and survival
IRIS trial
Randomised controlled trial for imatinib
RCT is the gold standard for testing the efficacy of new drugs in patients
It typically compares the new drug against standard treatment
RCT compared imatinib to IFNalpha . 553 patients in each arm, there was cross over
Results: progression free survival on imatinib is better than previous therapy
Response milestones
Baseline- risk stratify long term score (ELTS)
Haematological: normal blood counts at 1 month
Molecular : BCR::ABL
-<10% 3 months
-<1% 6 months (complete cytogenetic response)
-<0.1% 12 months (major molecular response)
<0.1% any time onward
Minimal residual disease MRD monitoring of BCR-ABL PCR transcript levels an integral part of management of CML patients on TKI inhibitors
BCR-ABL transcript numbers expressed as log reduction in patients responding to treatment
You must take the drug (imatinib) >90% of the time to get an adequate response
If you have gotten down to that level your life expectancy is the same as anyone else
BCR/ABL mutations are the most frequently reported mechanism of resistance to imatinib
Kinase domain mutations occur in 30-50% of cases of acquired resistance. Mutations fall into 4clusters
Resistance manifests itself through different mechanisms causing
-changes to the stability of the BCR-ABL conformation
-reduction in binding efficiency of imatinib
Next generation BCR-ABL inhibitors are active when the disease is resistant to imatinib
Nilotinib
Dasatinib
Bosutinib
Ponatinib. T315I activity
Asciminib. Allosteric inhibitor- not the ATP pocket
Next generation nilotinib is more effective than imatinib for newly diagnosed chronic myeloid leukaemia
Nilotinib versus imatinib for newly diagnosed chronic myeloid leukaemia
Progression to the accelerated phase or blast crisis 14 patients:
12 patients 4.8% receiving imatinib
2 patients 0.7% receiving 300mg of nilotinib
3 patients (1.3%) receiving 400mg of nilotinib
Haematopoietic stem cell transplant
High dose (myeloablative) chemotherapy or chemo-radiotherapy for recipient- kills leukaemic cells and existing marrow components= conditioning
Re-infusion of haematopoeitic stem cells
-autologous cells (collected if marrow not involved)
-allogeneic from HLA-matched donor (sibling or unrelated)
Pre-engraftment and post transplant
-extreme vulnerability to complications of infection, bleeding etc immunosuppressed
Establishing a chimera= donor haematopoiesis/immune cells, recipient tissues, you are yourself but blood is from someone else
Allogeneic HSCT remains only curable option
Works well chances of survival reasonably good for young patients
But only around 30% patients rate eligible for HSCT because:
-age
-morbidity
-donor availability
