Neoplasm 4 Flashcards Preview

Mechanisms of Disease > Neoplasm 4 > Flashcards

Flashcards in Neoplasm 4 Deck (11):

What factors influence survival rates for cancer?

Factors affecting survival rates include age and general health status, the tumour site, the tumour type, the grade (i.e. differentiation), the tumour stage (see below) and the availability of effective treatments.


What is tumour stage and what is TNM staging?

The tumour stage is a measure of the malignant neoplasm’s overall burden. The most common method for assessing the extent of tumour is the TNM staging system that is standardised across the world. T refers to the size of the primary tumour and is typically expressed as T1 through to T4. N describes the extent of regional node metastasis, for example N0 to N3. M denotes the extent of distant metastatic spread, e.g. M0 or M1. For a given cancer the T, N and M status are then converted into a stage from I to IV. The details vary for each cancer.


Describe the Ann Arbor staging system of Lymphomas

Lymphoma has its own special system called Ann Arbor staging.
Stage I indicates lymphoma in a single node region, stage II indicates two separate regions on one side of the diaphragm, stage III indicates spread to both sides of the diaphragm, and stage IV indicates diffuse or disseminated involvement of one or more extra -lymphatic organs such as bone marrow or lungs.


What is Tumour Grade and what is it most useful for?

Tumour grade describes the degree of differentiation of a neoplasm. In general, grading of malignant neoplasms is not as standardised as for staging. Typically G1 is well -differentiated, G2 is moderately differentiated, G3 is poorly differentiated and G4 is undifferentiated or anaplastic.

Tumour grade is more important for planning treatment and estimating prognosis.


What is the difference between adjuvant and neoadjuvant treatment?

Adjuvant treatment is given after surgical removal of a primary tumour to eliminate subclinical disease. Neoadjuvant treatment is given to reduce the size of a primary tumour prior to surgical excision.


Describe how radiotherapy works

Radiotherapy is focused on the tumour with shielding of surrounding healthy tissue. It is given in fractionated doses to minimise damage to normal tissues. X -rays or other types of ionising radiation are used and this kills rapidly dividing cells, especially in G2 of the cell cycle. This is because high dosage causes either direct or free-radical induced DNA damage that is detected by the cell cycle check - points, triggering apoptosis. Double -stranded DNA breakages cause damage to


Describe how Chemotherapy works

Chemotherapy drugs affect proliferating cells in various ways. Several classes of chemotherapy agents exist. Antimetabolites mimic normal substrates involved in DNA replication. Platinum-based drugs cross-link the two strands of the DNA helix. Antibiotics act in several different ways but mainly by interfering with DNA replication in some way.


Describe how hormone therapy works

Hormone therapy is relatively non-toxic to certain malignant tumours. Selective oestrogen receptor 9 modulators (SERMs), such as tamoxifen, bind to oestrogen receptors, preventing oestrogen from binding. They are used to treat hormone receptor-positive breast cancer. Androgen blockade is used for prostate cancer.


Give some examples of cancer specific medications

A quarter of breast cancers have gross over-expression of the HER-2 gene and Herceptin can block Her-2 signalling. Chronic myeloid leukaemia (CML) shows a chromosomal rearrangement (t9:22) creating an abnormal ‘Philadelphia’ chromosome in which an oncogenic fusion protein (BCR-ABL) is encoded. Imatinib inhibits the fusion protein.


Give an example of some tumour markers

Tumour markers include
1. Hormones (e.g. human chorionic gonadotrophin released by testicular tumours),
2. Oncofetal Antigens (e.g. alpha fetoprotein released by hepato cellar carcinoma),
3. Specific proteins (e.g. prostate-specific antigen released by prostate carcinoma)
4. Glycoproteins (e.g. CA-125 released by ovarian cancer).


Give some examples of problems that can occur with screening

Screening can have problems such as lead time bias (i.e. finding it earlier but not being able to treat it so survival times appear longer), length bias (screening favours finding slow growing cancers whilst fast growing will reach a point at which they can be diagnosed clinically) and over diagnosis (diagnosis where the cancer won’t kill them causing unnecessary worry and also false positives).