Which agent in R-CHOP is most likely to cause constipation?

• A. Doxorubicin
• B. Cyclophosphamide
• C. Vincristine
• D. Rituximab

Answer: (C)

Vincristine is the agent in R-CHOP most likely to cause constipation because its main toxicity is neurotoxicity, particularly affecting autonomic nerves that control gut motility. This leads to decreased peristalsis and can result in constipation, and in some cases ileus. The other drugs tend to produce different adverse effects: doxorubicin is more associated with cardiotoxicity and mucositis, cyclophosphamide with hemorrhagic cystitis and bone marrow suppression, and rituximab with infusion reactions and infections. So when constipation occurs in this regimen, vincristine is the most plausible culprit. Management focuses on monitoring bowel function and implementing supportive measures such as stool softeners or laxatives as appropriate, with dose or schedule adjustments if constipation becomes severe.