module 3 review questions Flashcards
Describe the two processes that must occur in order for normal renewal and repair to take place.
Cell proliferation: an increase in the number of cells as a result of cell growth and cell division
Cell differentiation: cells acquiring the characteristics of the tissue that they make up
Describe benign tumours (4 points). How are they generally named?
Growth is usually slow and may come to a stop
Made of fairly well-differentiated cells and well-organized stroma (connective tissue framework)
Do not invade beyond their capsule
No metastasis
Generally named for the tissues from which they arise, with the suffix “oma”
Can benign tumours still cause problems? How?
Can still be a problem if the growth interferes with function of surrounding tissue or inappropriately produces hormones
Describe malignant tumours (4 points).
More rapid growth rate
Loss of differentiation (anaplasia) and tissue organization (a spectrum from low to high grade) cells are pleomorphic (different sizes and shapes)
Lack a capsule and invade nearby blood vessels, lymphatics and surrounding structures
Most deadly characteristics: the ability to metastasize (spread far beyond the tissue of origin)
How are malignant tumours generally named?
Named for cell type from which they originate with “carcinoma” (epithelial tissue) or “sarcoma” (from mesenchymal tissue (connective, bone muscle))
What does “adeno-” at the beginning of a name mean?
From glandular tissue
Define lymphoma and leukemia.
Lymphomas: from lymphatic tissue
Leukemias: cancers of blood forming cells
Describe the two categories of malignant neoplasms.
Solid: initially confined to specific tissue/organs tumours
Hematologic: cells normally found in blood/lymph tumours
From what tissue type are most human cancers derived?
Transformation of epithelial cells
Describe “carcinoma in situ”. Where can this occur?
Refers to a growth with malignant characteristics (increased proliferation rate and atypical cells) in epithelial tissue that has not (yet) invaded local tissue
Occur in breast, cervix, skin, stomach
Describe eight cancer cell characteristics.
Genetic instability: there is a high frequency of mutations in cancer cells
The cell must become independent of external growth signals: able to make their own, don’t need any, extremely sensitive to growth factors so will respond to extremely low levels
Loss of contact inhibition (normal cells usually stop growing when they come into contact with each other)
Decrease in cell adhesion (normal cells have membrane structures that allow them to stick together – cancer cells have less of these and can then more easily be shed from a tumour, increasing the possibility of metastasis)
Loss of anchorage dependence – normal epithelial cells will ide if they are not attached to another cell, or to an underlying extracellular matrix. Cancer cells can survive and grow under conditions that normal cells can’t
Production of unusual antigens (cell surface markers that are identified as foreign by the immune system), enzymes, or hormones that are not made by the tissue of origin
Able to divide without limit – telomeres are sections on the end of each chromosome that get shorter with each division. Cancer cells have a very active enzyme called telomerase, that can lengthen telomeres. Therefore, they can divide without a limit
Altered metabolism, increasing anaerobic respiration
What is metastasis?
The spread of cancer cells from the original site to distant organs and tissues
Describe the difference in the local growth of benign vs malignant tumours.
Benign: pushes on surrounding connective tissue that eventually forms a capsule around the growth
Malignant: helped by enzymes made by the cancer cells that break down cells and connective tissue of surroundings. Growth is by sending “crablike” extensions into surrounding tissue
Identify the difference in the route of spread of growth between carcinomas vs sarcomas.
Carcinoma: epithelial tissue derived, spread through lymph
Sarcomas: fibrous tissue derived, spread through blood
What is a “sentinel node”?
If the spread is through the lymph, the tumour cells lodge first in the initial lymph node that drains that area
Describe six possible local effects of a tumour.
Compression: e.g. brain tumour: headaches, nausea, loss of consciousness, death
Obstruction: e.g. blockage to airways
Infarction: growth of mass can obstruct blood vessels, causing local necrosis of tissues
Hemorrhage: damage to blood vessels
Rupture
Effusions: inappropriate amounts of fluid
Describe nine systemic effects of cancer, including how the cancer and/or the treatment can be the cause of the problem. (Review: what is the term for manifestations of a disease that are caused by medical treatment?)
Paraneoplastic: symptoms triggered by a cancer, but not caused by direct local effects of the tumour mass
Pain: little to none in early stages, can be strong in later stages. Can result from pressure, stretching, inflammation
Fatigue: not relieved by sleep or rest. May be due to sleep disturbances, various biochemical changes
Cachexia: loss of body mass due to metabolic disturbances caused by a disease and cannot be reversed nutritionally
Anemia: caused by chronic bleeding, malnutrition, chemo
Leukopenia and thrombocytopenia: caused by tumour invasion of bone marrow, chemo, radiation
Infection: due to loss of immune cells due to reasons above
GI tract: relies on rapidly multiplying tissue which is the type of tissue affected by chemo and radiation
Hair and skin: also due to rapidly growing tissue being affected by therapeutic agents
What is the multistep theory of carcinogenesis?
Beginning: mutation that makes one cell more likely to divide (hyperplasia)
One of the descendant cells experiences another mutation that causes its descendants to look abnormal (dysplasia)
Yet another mutation eventually occurs in a further descendant cell which results in very abnormal structure, loss of differentiation, and loss of contact inhibition between the cells; however, they are still confined to the epithelial layer from which the original cell arose (carcinoma in situ)
Additional mutations may occur that enable them to invade neighbouring tissues and shed cells into the blood or lymph (malignant)
The escaped cells may establish new tumours at other locations in the body (metastasis)
What is the effect of age on the development of cancer (why is cancer more prevalent with age)?
It requires several mutations to produce a malignant tumour, the older a person is, the greater the chance that these mutations have occurred
Why is the alteration of tumour suppressing genes said to be recessive in effect?
These are usually the type of genes that are involved in cancer that can be inherited (individuals can inherit a defective allele, but have the protection of another allele. However if the other allele becomes inactivated, then a tumour can develop)
Describe and give an example for two other factors that could contribute to the development of cancer.
Changes in the control mechanisms that govern which genes are expressed
Changes in metabolic pathways inside the cell (e.g. loss of DNA repair machinery that could fix an oncogene)
Be familiar with the causative factors of cancer, including: a. Inflammation b. Viral and bacterial infections c. Environmental/lifestyle interactions d. Heredity e. Immunological mechanisms f. Age g. Chemical carcinogens h. Low strength (solar) radiation and high strength (nuclear) radiation
Chronic inflammation has been recognized for close to 150 years as being an important factor in the development of cancer & inflammation and cancer both involve the migration of neutrophils, lymphocytes and macrophages, with the release of factors that stimulate the growth of cells and blood vessels. Inflammatory cells also release compounds that can promote mutations
Viral: a number of viruses have been associated with cancer, through alteration of the DNA that the virus may cause, or through inflammation caused by the viral disease:
80% liver cancer associated with chronic hepatitis caused by HBV & HCV
All cervical cancer caused by HPV
EBV virus infects B cells and stimulates growth
Bacterial chronic infection with helicobacter pylori has been linked to gastric carcinoma
Environmental: cigarette smoking, excessive alcohol consumption, poor diet, obesity, lack of exercise, exposure to UV
Describe the stages of carcinogenesis.
Initiation: Exposure to carcinogenic agent, Irreversible mutations to genome, May be many small doses over time, Cells in mitosis or meiosis
Promotion: Cytokines and growth factors begin to induce cell proliferation
Progression: Tumour cells eventually acquire all the characteristics needed to invade and metastasize to other tissues
Differentiate between CT, MRI and PET scans.
CT – can see larger areas than with one x-ray and can check for metastasis
MRI – provides more soft tissue detail than CT, but more expensive and time-consuming
PET – like CT, but uses a biologically active molecule attached to a tracer, to show metabolically active tissue
Describe the 4 stage system of classifying cancer.
Stage 1: confined to origin
Stage 2: local invasive
Stage 3: spread to local lymph nodes
Stage 4: spread to distant sites
Describe WHO’s TNM system.
TNM: tumour size (t) lymph node involvement (n) extent of metastasis (m)
Name the 3 main treatments for cancer and describe the basis on which they work.
Chemotherapy: targets metabolic pathways – hopefully a cancer cell is more sensitive to a particular chemical.
radiation therapy: targeted cells die through molecular damage caused by ionizing radiation
surgery
Why are chemotherapeutic agents often given as “cocktails”?
Usually in combinations, to decrease the amount given of any one drug and increasing attack on cancer cells (some cells in a tumour may be resistant to one drug, but susceptible to another one in the cocktail given)
What is brachytherapy?
Can be through an external beam, or by placing
small radioactive capsules in the affected area
(brachytherapy) – e.g., cervical, prostate, head and
neck cancers.
Describe induction, adjuvant and neoadjuvant chemotherapies.
– Can be given alone (induction), or in combination with
surgery (either after (adjuvant), to eliminate small
metastasized tumours, or before (neoadjuvant), to
minimize removal of normal tissue)
What are three uses for surgery other than complete removal of the tumour?
May be used prophylactically (women with BRCA1/2
mutations)
– Obtaining tissue for biopsies (if surgery is being used for
diagnosis)
– Establishing staging information by observing and sampling
local lymph tissue
