A 58-year-old man has a rectal cancer at 7 cm from the anal verge. MRI shows T3N1 disease with threatened circumferential resection margin (CRM <1 mm). The optimal management sequence is:
- A Long-course chemoradiotherapy (LCRT) followed by reassessment and TME ✓
- B Upfront low anterior resection with total mesorectal excision (TME)
- C Short-course radiotherapy (5×5 Gy) followed by immediate surgery
- D Abdominoperineal resection without neoadjuvant therapy
Correct answer: A. Long-course chemoradiotherapy (LCRT) followed by reassessment and TME
Explanation
Threatened or involved circumferential resection margin on preoperative MRI is an indication for long-course chemoradiotherapy (45-50.4 Gy with concurrent 5-fluorouracil) before surgery, aiming to downstage the tumor and achieve clear CRM. Short-course radiotherapy (5×5 Gy) is generally preferred for resectable T3 rectal cancers with clear CRM. A positive CRM (≤1 mm) is the strongest predictor of local recurrence after rectal cancer surgery; neoadjuvant LCRT significantly reduces this risk.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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