Key Facts

Chemotherapy remains a cornerstone of cancer treatment, using cytotoxic drugs to target rapidly dividing cells. Understanding mechanisms of action, toxicity profiles, and supportive care measures is essential for safe and effective administration.

Epidemiology

• Approximately 30% of cancer patients receive chemotherapy as part of their treatment
• Both curative and palliative roles depending on cancer type and stage

Aetiology

• Not applicable (treatment modality)

Pathophysiology

• Cytotoxic drugs exploit the cell cycle by targeting DNA synthesis, repair, and cell division
• Damage to DNA triggers apoptosis in susceptible cells
• Combination regimens use drugs with different mechanisms to maximise cell kill and minimise resistance (Norton-Simon hypothesis, Goldie-Coldman hypothesis)
• Log-kill hypothesis: each cycle of chemotherapy kills a constant fraction of tumour cells

Indications for Chemotherapy

• Neoadjuvant: shrink tumour before surgery (e.g. breast cancer, oesophageal cancer)
• Adjuvant: reduce recurrence risk after curative surgery (e.g. colorectal, breast)
• Curative: primary treatment (e.g. leukaemia, lymphoma, testicular cancer)
• Palliative: improve symptoms and prolong survival (e.g. metastatic disease)

Common Side Effects

• Bone marrow suppression: neutropenia (day 7-14 nadir), anaemia, thrombocytopenia
• GI toxicity: nausea/vomiting, mucositis, diarrhoea
• Alopecia: reversible with most agents
• Fatigue: most common reported symptom
• Infertility: depends on agent and cumulative dose

Red Flags

• Neutropenic sepsis (fever ≥38°C with neutrophils <0.5 × 10⁹/L)
• Tumour lysis syndrome (TLS)
• Anaphylaxis during infusion
• Extravasation of vesicant drugs

Bedside

• Observations (temperature, HR, BP)
• Performance status assessment
• Oral examination (mucositis grading)

Bloods

• Pre-cycle: FBC (ANC >1.5 × 10⁹/L for most regimens), U&Es, LFTs, eGFR
• During treatment: regular FBC monitoring (nadir typically day 7-14)
• Tumour markers as appropriate
• If febrile: blood cultures (peripheral and from central line), lactate, CRP

Imaging

• Response assessment: CT scan typically after 2-3 cycles
• PET-CT for interim response in lymphoma

Special Tests

• Cardiac assessment (echocardiogram/MUGA scan): before anthracyclines
• Audiometry: before cisplatin
• Pulmonary function tests: before bleomycin
• GFR measurement: before platinum-based chemotherapy
• DPD deficiency testing: before fluoropyrimidines (5-FU, capecitabine) - DPYD genotyping

Non-pharmacological

• Pre-treatment counselling: side effects, fertility preservation options (sperm banking, oocyte cryopreservation)
• PICC line or port insertion for repeated IV access
• Scalp cooling to reduce alopecia (where available)
• Dietary advice and nutritional support

Pharmacological

• Antiemetics (emetogenicity-dependent per NICE/MASCC guidelines):
  • High emetogenic (cisplatin): ondansetron 8mg + dexamethasone 12mg + aprepitant 125mg/80mg/80mg (days 1-3)
  • Moderate: ondansetron 8mg + dexamethasone 8mg
  • Low: dexamethasone 4mg or metoclopramide 10mg
• G-CSF (filgrastim 5mcg/kg/day or pegfilgrastim 6mg): primary prophylaxis if febrile neutropenia risk >20%
• Allopurinol or rasburicase: TLS prophylaxis
• Dexrazoxane: cardioprotection with anthracyclines (selected patients)
• Mesna: urothelial protection with cyclophosphamide/ifosfamide
• Folinic acid (leucovorin) rescue: after high-dose methotrexate

Surgical/Interventional

• Central venous access device insertion (PICC, Hickman line, portacath)
• Fertility preservation procedures (pre-chemotherapy)

Referral Criteria

• All chemotherapy prescribed by oncologists within MDT framework
• Neutropenic sepsis: immediate assessment in oncology assessment unit or A&E
• Extravasation: immediate management per local protocol

• Highly variable depending on cancer type, stage, and treatment intent
• Curative regimens (e.g. lymphoma, testicular): 80-95% cure rates
• Adjuvant chemotherapy for breast cancer: reduces recurrence by approximately 30%
• Palliative chemotherapy: extends median survival by weeks to months in most metastatic solid tumours
• Treatment-related mortality: approximately 1-3% for most standard regimens
• Late effects: secondary malignancy (leukaemia after alkylating agents), cardiotoxicity, infertility

Common Chemotherapy Drug Classes

CTCAE Grading (Common Terminology Criteria for Adverse Events)