Successful rapid desensitization with 5-fluorouracil in a patient with metastatic sigmoid colon cancer: A case report

Introduction 5-Fluorouracil (5-FU) is an antimetabolite widely used in colorectal, gastric, breast, and other solid tumors. Hypersensitivity reactions are uncommon but may be severe. Case Report We report a 63-year-old woman with metastatic sigmoid colon cancer who developed an anaphylactic reaction during the second course of a 5-FU—containing regimen, specifically following the bolus infusion. Skin prick and intradermal tests performed four weeks later were negative. Management & Outcome As no equally efficacious alternative existed within the planned regimen, rapid intravenous desensitization was performed using a 16-step protocol with four dilution solutions. Desensitization was completed without adverse events, and the subsequent 48-h continuous 5-FU infusion was also well tolerated. Discussion This case adds to the limited literature on 5-FU desensitization and underscores its feasibility and safety in agent-dependent patients.