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Bevacizumab Fistula — SCE Medical Oncology MCQ

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ModerateImmunotherapy & Targeted TherapyBevacizumab FistulaSCE Medical Oncology

A 60-year-old woman on bevacizumab for CRC develops a non-healing perianal fistula. She has no evidence of disease at the perianal site. What is the likely mechanism?

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Correct answer: C — Anti-VEGF impairment of wound healing — fistula formation is a recognised complication of bevacizumab (especially in perianal/pelvic regions with prior surgery or radiation); bevacizumab should be held and surgical assessment obtained

Bevacizumab increases fistula risk through anti-VEGF-mediated impaired tissue healing, particularly in pelvic/perianal regions. Risk factors: prior pelvic surgery, prior radiotherapy, concurrent tumour involvement, and ongoing bevacizumab therapy. Management: hold bevacizumab (minimum 28 days), surgical assessment for drainage/repair, and reassess risk-benefit before restarting. For cervical cancer patients on bevacizumab, vesicovaginal and rectovaginal fistulae are specific concerns (~5-10% in GOG-240).

Reference: BNF Bevacizumab; ESMO Supportive Care; GOG-240 safety