Cancer chemotherapy Flashcards
3 main approaches to dealing with established cancers:
- 1) Surgical excision
- 2) Radiotherapy
- 3) Chemotherapy
Four types of traditional agent
- Alkylating agents
- Anti metabolites
- Cytotoxic antibiotics
- Plant derivatives
Main drawbacks of chemotherapy of cancer
- Target cell proliferation not the more lethal properties of invasiveness and metastasis
- Non-specific cell killers rather than being aimed at the particular changes which make a cell malignant
- The development of resistance (particularly multidrug resistance) to anticancer drugs
- Leaves some remaining cells
- Healthy cells which have a high rate of growth and multiplication include cells of the bone marrow, hair, GI mucosa and skin therefore side-effects often relate to these body systems
- Severity of side effects varies between drugs – the summary of product characteristics (SPC) can be referred to on the eMC website for details on specific side-effects of each drug.
- May be drug specific e.g. anthracyclines and cardiotoxicity; vinca alkaloids and neuropathy; high dose cisplatin and ototoxicity
- Side effects often occur 7-14 days post treatment. These can be cumulative over many cycles
- Patient compliance due to side-effects Not completing the therapy regimen
Specific side-effects: Tumour Lysis Syndrome
- An acute side-effect and a metabolic emergency
- Occurs due to rapid cell lysis (death) & large amounts of cell metabolites in blood.
- It is characterized by hyperuricaemia, hyperphosphataemia, hyperkalaemia and hypocalcaemia
- If untreated can lead to acute renal failure, cardiac arrest and death.
- Risk assess patient prior to chemotherapy
- Monitor and respond to deranged urea and electrolytes / fluid balance: dialysis may be required
Specific side-effect: Bone Marrow
- Myelosuppression – reduced production of cells which provide immunity, oxygen transport and clotting common with many chemotherapy agents (except Vincristine and Bleomycin)
- Only actively dividing cells in the bone marrow are affected (i.e. stem cells)
- Monitor full blood count prior to then daily during treatment cycles
- Occasional use of recombinant human granulocyte-colony stimulating factors (e.g. Filgrastim) recommended to reduce incidence/duration of myelosupression
- Cells with shorter life span are more affected
Specific side-effect: Gastro-intestinal
loss of appetite
nausea and vomitting
Specific side-effect: Gastro-intestinal constipation
- Due to reduction in gastric motility, reduced fluid intake and activity, side-effects of concurrent anti-emetics e.g. granisetron.
- Management – add laxatives
Specific side-effect: Gastro-intestinal diarrhoea
- can cause severe dehydration and electrolyte disturbances
- Manage by stopping oral chemo
- May need to give IV fluid support
- Consider adding anti-diarrhoeal e.g. loperamide
Specific side-effect: Mucositis
- Ulceration, dry mouth, pain, taste alterations
• Prevention and management:
• Assess the oral cavity regularly
• Encourage good oral hygiene and regular dental visits
• Anti-bacterials and anti-virals
Specific side-effect: Other
- Fatigue: Often multi-factorial, treat cause if known, involve physio/occupational therapists in care
- Body image side-effects – hair loss, weight loss/gain, appearance of intervention wounds
- Peripheral neuropathy – counsel patient about need for care if injured, consider analgesia for nerve pain
- Altered renal function – care with drug choices, doses and frequency
- Delayed effects: infertility, secondary malignancy
personalised medicine
– genomic/genetic testing
– proteomic profiling
– metabolomic analysis (study metabolites)
preventative care aims
i. improved prevention based on underlying predisposition;
ii. earlier diagnosis of disease as a result of identifying abnormality earlier;
iii. more precise diagnosis based on cause; and
iv. targeted interventions through the use of companion diagnostics to identify and stratify patients for effective treatments.
pharmacogenetics
the study of the way a patient’s genome affects their response to drugs
Testing: in pharmacogenetics
Germline variants in the dihydropyrimidine dehydrogenase (DPYD) gene can confer an increased risk of severe toxicity when a patient is treated with the fluoropyrimidines, capecitabine or 5-fluorouracil.
