Anaesthetic Implications of Chemotherapy and Radiotherapy

1. Cardiovascular

• Anthracyclines (doxorubicin, daunorubicin) cause dose-dependent, often irreversible dilated cardiomyopathy and arrhythmias; cardiotoxicity may only manifest under the stress of anaesthesia/surgery. Preoperative echocardiogram (LVEF) is mandatory if cumulative dose is significant.
• Mediastinal/thoracic radiotherapy causes pericardial fibrosis/constrictive pericarditis, accelerated coronary artery disease, valvular fibrosis and conduction defects - all of which reduce tolerance to the cardiovascular effects of anaesthetic agents and positive pressure ventilation (Fuster and Hurst's The Heart, 15th Ed).
• Trastuzumab and some tyrosine-kinase inhibitors also cause reversible LV dysfunction.

2. Respiratory

• Bleomycin causes pulmonary fibrosis and is notorious for triggering acute lung injury/ARDS if the patient is exposed to high inspired oxygen concentrations perioperatively - FiO2 should be kept as low as safely possible and high-flow oxygen avoided even months after treatment (Fischer's Mastery of Surgery; Campbell-Walsh Urology).
• Busulfan, cyclophosphamide, methotrexate also cause pulmonary fibrosis/pneumonitis, reducing pulmonary reserve and increasing risk of postoperative respiratory failure.
• Thoracic/mediastinal radiotherapy produces radiation pneumonitis and later fibrosis, restrictive lung physiology, and reduced diffusion capacity - relevant to one-lung ventilation or major thoracic/abdominal surgery.
• Head and neck radiotherapy causes tissue fibrosis distorting anatomy, making airway assessment, mask ventilation, laryngoscopy and intubation difficult, and increasing risk of a difficult/failed airway.

3. Renal and Haematological

• Cisplatin, ifosfamide, some targeted agents cause nephrotoxicity - check renal function, avoid further nephrotoxic drugs (NSAIDs, aminoglycosides, contrast), adjust drug dosing and fluid management accordingly (Comprehensive Clinical Nephrology; Harrison's Principles of Internal Medicine).
• Cyclophosphamide causes haemorrhagic cystitis; myelosuppressive agents cause anaemia, neutropenia (strict asepsis, blood product planning) and thrombocytopenia (bleeding risk, caution with regional/neuraxial techniques).

4. Neurological

• Vincristine, platinum agents, taxanes cause peripheral neuropathy - document pre-existing deficits before regional anaesthesia to avoid medicolegal ambiguity about causation; autonomic neuropathy can cause perioperative haemodynamic instability.

5. Other practical considerations

• Radiotherapy-induced skin/soft tissue fibrosis can distort veins (difficult IV access), limit neck extension/mouth opening, and distort landmarks for regional blocks or central line placement.
• General debility, nausea/vomiting, malnutrition and electrolyte derangements from chemotherapy affect fasting status, aspiration risk and drug pharmacokinetics.
• Some chemotherapy agents interact with anaesthetic drugs (e.g., cyclophosphamide can prolong suxamethonium action via reduced pseudocholinesterase).