Principles of cancer therapy Flashcards
What is the clinical presentation of cancer?
It can be symptoms arising from the primary tumour eg bleeding, bowell obstruction, pain. It can present as metastatic spread eg headaches due to spread to the brain, problems with lymph nodes, breathlessness due to spread to the lungs etc. It can also present with paraneoplastic syndromes such as hypercalcaemia, autoimmune diseases or things like finger clubbing.
What happens with diagnosis, staging and functional assessment of cancer?
Diagnosis - must be done by histology
Staging - generally TNM staging to assess the extent of development of the tumour
Functional assessment - how likely is the patient going to be able to cope with the disease and treatment (eg resection of the lung)
What is the most effective cure for cancer?
Surgery
How does radiation kill cancer?
Radiation damages DNA (breaks the double strand) and generates free radical that damage membranes and proteins etc so the cells die.
What does chemotherapy do?
It uses chemicals to kill disease causing cells in the body - bacteria, fungi cancer.
In contrast drug therapy uses chemicals to modulate or alter bodily processes.
What is selective toxicity?
This is the goal of cancer chemotherapy. This allows for the killing of abnormal cells without having an effect on normal cells (like drug therapy does). This is achieved by exploiting the differences between normal host cells and disease producing cells.
What is the therapeutic index?
It is the ratio of the dose of drug causing toxic effects divided by the dose required to produce desired effect.
What is similar between tumour growth and the rate of chemotherapy killing?
Tumour growth occurs through the dividing of cells. This is constant - eg the time taken for 1 cell to become 2 cells is the same time for 100 cells to become 200 cells.
This is the same for the action of chemotherapy. (each dose kills a constant proportion of cells). Eg one dose drops the number of cells from 2 mil to 1 mil or like 2 cells to 1 cell.
What are some of the adverse effects of cancer chemotherapy?
Antiproliferative effect - inhibition of fast multiplying cells results in dry mouth, immune supression and hair loss etc
Mutagenesis - can result in second cancers
Sex steroid deficiency - inhibition of production of sex hormones results in decreased libido, flushing etc.
What is the definition of cancer?
A disease of groups of cells that divide and grow without regard to normal limits thus resulting in an acummulation of abnormal cells.
It is often caused by mutations to oncogenes or tumour suppressor genes. The results in abnormailities in DNA.
What is a newer way to treat cancer other than the non selective chemotherapy and immunotherapy?
Targeted cancer therapy - these are drugs treatments that inhibit oncoproteins that drive tumour development. These are identified via genetic testing.
Small molecular drugs bind to growth factor receptors or block specific enzymes.
Monoclonal antibodies bind to growth factors or their receptors.
What is a condition where there has been successful targeted cancer therapy? and what is its mechanism of action
Chronic myeloid leukaemia
Imatinib binds to ATP binding site of the cancer fusion protein/enzyme this stopping growth of the cancer. This works well as this fusion protein is only produced by the chronic myeloid leukaemia cells so wont affect normal body cells.
