Cancer Chemotherapy Flashcards
What are the limitations of anti-cancer therapy/
- cancers are good at evading the immune response
- cancer originates from the body’s own cells and so the body has poor defences
- cancer cells have the same biochemistry as normal body cells which makes targeting difficult
What are the 3 main approaches to dealing with cancer?
- surgical excision
- radiotherapy
- chemotherapy
What are the 4 traditional agents used for cancer?
- alkylating agents
- antimetabolites
- cytotoxic antibiotics
- plant derivatives
Describe the mechanism of action of alkylating agents
- can form covalent bonds with nucleophilic substances in the cancerous cell
- bifunctional and causes intrastrand cross-linking of DNA
What are the 6 major groups of alkylating agents and some examples?
- nitrogen mustards (eg. cyclophosphamide)
- ethylenimines (eg. thiotepa)
- alkylsulphonates (eg. busulphan)
- hydrazines and triazines (eg. temozolomide)
- nitrosoureas (eg. lomustine/carmustine)
- platinum based compounds (eg. cisplatin)
What are the 3 major groups of antimetabolites and examples?
- antifolates (eg. methotrexate)
- antipyrimidines (eg. 5-FU, gemticibane)
- antipurines (eg. mercaptopurine, thioguanine)
What are some examples of cytotoxic antibiotics?
- anthracyclines
- dactinomycin
- bleomycin
- mitomycin
What are the 2 mechanisms of action of plant derivatives?
- spindle poisons: affect microtubule function and prevent mitotic spindle formation
- top I/II inhibitors
What are examples of plant derivates?
- spindle poisons:
- vinca alkaloids eg. vincristine, vinblastine
- taxanes eg. paclitaxel, doxetaxel
- top I/II inhibitors:
- camptothecins eg. irinotecan (top I)
- etoposide eg. DNA binding (top II)
What are the drawbacks of chemotherapy?
- it targets cell proliferation not invasiveness/metastasis
- non-specific cell killers so can kill healthy cells
- development of resistance
- leaves remaining cells
- side effects which can affect body systems that have high cell growth rate
- side effects which are drug specific
- side effects often post treatment
- patient non-compliance due to side effects (not completing therapy)
Describe what tumour lysis syndrome is
- acute side effect of chemo
- metabolic emergency
- due to rapid cell lysis and large amounts of cell matabolites in blood
- characterised by hyperuricaemia, hyperphosphataemia, hyperkalaemia, hypocalcaemia
- if left untreated can lead to acute renal failure, cardiac arrest and death
How would you manage and prevent tumour lysis syndrome?
- manage it by monitoring and responding to deranged urea and electrolytes/fluid balance: may need dialysis
- prevent by risk assessing patient prior to chemotherapy
Describe the side effect of chemotherapy on the bone marrow
- myelosuppression; reduced production of cells that provide immunity, oxygen transport and clotting
- only actively dividing cells in bone marrow
- cells with shorter life span more affected
How would you manage and treat myelosuppression?
- monitor full blood count prior to and then daily during treatment cycles
- occasional use of recombinant human granulocyte- colony stimulating factors to reduce incidence/duration of myelosuppression
What are the GI side effects of chemotherapy?
- nausea and vomiting
- loss of appetite
- constipation (due to reduction is gastric motility/fluid intake/activity)
- diarrhoea (can cause severe dehydration and electrolyte disturbances)
- ulceration, dry mouth, pain, taste alterations
