Principles of cancer therapy Flashcards
5 most common canceres in NX
prostate colorectal breast melanoma lung
3 main pathio-physiological processes causing cancer clinical presentation
- primary tumor and local effects
- metastasis and distant efeects
- paraneoplastic syndromes
How to diagnose cancer
Tumor biopsy and histopathology (pathological diagnosis)
Identify tissue of origin, stage, grade, prognostic markers
Staging
Determines the extent of involvement/spread
Functional assessment
How is the patient likely to cope with both the disesae and treatment
Princples of cancer treatment
- is surgical resection or curative treatment possible. If so then radical treatment is justifiable but not if benefits are lilely to be limited to palliation
- what treatment modalities are required for the best outcome (srugery, radio, chemo)
What is the most effective treatment in curing cancer
Surgery - complete resection /excision with a margin of normal tissue
Also used in diagnosis, staging, local control and palliation i.e. to bypass an obstruction
What are the principles of radiation therapy
> local form of cancer treatment
IONISING radiation: energy from the radiation damages DNA/breaks the double strands and generates free radicals that damage membranes, proteins and organelles and induce cell death
External beam radiotherapy
Is planned according to treatment field/location, dose to the tumor and so normal tissue and the number of treatments
Often used in curative treatment for head and neck cancer
Chemotherapy
Chemotherapy is the process of using chemicals to kill the disease causing cells.
This is different to drug therapy which uses chemicals to MODULATE body processes like BP.
Chemo only WANTS to affect cancer cells while drug therapy wants affect normal cells to modulate body processes.
What is the goal of chemo…
SELECTIVE toxicity
Toxicity in the cancer cells without or with less effects in the normal host cells.
Selective toxicity is achieved by targeting differences between the cancer cells and normal cells
> unique target in the pathogen (cell wall in bacteria)
> target is the same but structurally different in the pathogen (i.e. same enz)
> target is FUNCTIONALLY different (mitotic activity)
What is the theraputic index
The therapeutic index is an important indicatior of selective toxicity
It is a ratio of the dose required to produce a toxic effect divided by the dose required to produce a desired effect
8 chemo drug mechanisms
- alkylating
- anti-topoisomerase
- anti-microtubule
- platinum based
- vascular targeting
- anti-metabolites
- targeted therapies
- hormonal agents
What kind of kinetics do tumor cells grow by and chemo kill by
FIRST ORDER
How do both chemo and cancer act by first order kinetics?
- tumor starts as one malingant cell, divides with CONSTANT DOUBLING TIME
- chemo: each dose kills a CONSTANT PROPORTION of cells no matter the starting number, repeated doses are required and continue after clinical disappearance
Tumor growth and chemo action act exponentially and this is shown via a log graph over time
Combination chemo?
Is more effective than single agents.
What is the criteria for combintation chemotherapy
- each drug needs to have some actiivty as a single agent
- need to have differing mechanisms of action
- need to have different side effects
Limits toxicity
Combination chemo for testicular cancer
BEP
Bleomycin
Etopside
CisPlatin
What are common adverse effects of chemo
- common
- are mostly related to the main pharm action of the drug so are perdicatble
- determine the dose and DI
- may be annoying, dangerous and limit compliance
- most are reversbie or clincally maangeabel i.e. nausea
Examples of side effects
- antiproliferatives cause myelosuppression, mucositis, alopecia, sterility
- mutagenesis can actually cause second cancers
- microtubule disturbances can cause peripheral nerve toxicity
- sex steroid deficiency can cause impotence, decreased libido
Chemo cure rate is high in
Acute lymphoblastic leukaemia (young)
Testicular cancer
Hodgkins
Chemo and surgery
Node positive breast cacner and colorectal cancers (micro metastatic disease) - been resected but high risk of recurrent cancer
Chemo and radio
Head and neck cancers
Cervical
Chemo as palliation
Improves symptoms and survival time and QoL
