What is the optimal management plan for a 39‑year‑old man with a 4.6 cm upper‑third rectal adenocarcinoma, moderately differentiated, clinical stage T3c N0?

Management of cT3c N0 High Rectal Adenocarcinoma

This patient requires neoadjuvant chemoradiotherapy followed by total mesorectal excision (TME) with low anterior resection (LAR), as preoperative radiotherapy is standard for T3 tumors to reduce local recurrence risk. 1, 2

Neoadjuvant Treatment Strategy

Standard Long-Course Chemoradiotherapy (Preferred)

• Deliver 45.0-50.4 Gy in 25-28 fractions over 5-5.5 weeks with concurrent capecitabine 825 mg/m² twice daily, 5-7 days per week during radiation. 3
• Alternative concurrent chemotherapy includes continuous infusion 5-FU 225 mg/m²/day, 7 days per week during the entire radiation period. 3
• A tumor boost of 4-6 Gy in 2-4 fractions may be added after 45 Gy to the primary tumor bed with a 2 cm margin. 3
• The clinical target volume must include the primary tumor with a 2-5 cm margin, the entire mesorectum, presacral lymph nodes, internal iliac lymph nodes, and obturator lymph nodes. 3

Alternative Short-Course Radiotherapy

• 25 Gy in 5 Gy/fraction over one week followed by immediate surgery is a convenient, simple, and low-toxic alternative, though long-course chemoradiotherapy is more commonly used for T3c disease. 1

Timing of Surgery

• Schedule surgery 8-10 weeks after completing chemoradiotherapy to balance tumor regression with acceptable morbidity. 3
• The optimal interval is 5-12 weeks, with longer intervals potentially increasing pathologic complete response rates. 3

Surgical Approach

Low Anterior Resection with TME

• LAR is the appropriate procedure for this upper rectal tumor, as it allows adequate distal clearance while preserving anal sphincter function. 2
• Achieve a minimum distal margin of 2 cm from the tumor edge. 1, 2
• Perform complete total mesorectal excision (TME) with sharp dissection along the mesorectal fascia to preserve autonomic nerves and minimize local recurrence. 2, 4
• Examine at least 6-8 (preferably 12) regional lymph nodes for proper staging. 1, 2

Technical Considerations

• Mobilize the left colon and splenic flexure to ensure tension-free anastomosis. 2
• Construct a colonic pouch to replace the rectal reservoir, which improves functional outcomes. 1, 2
• Consider a temporary diverting ileostomy, especially for low anastomoses. 2
• Ensure the circumferential resection margin (CRM) is negative (>1 mm from tumor). 2

Adjuvant Chemotherapy

• After surgery, administer six courses of bolus 5-FU plus folinic acid (days 1-5) if pathology reveals node-positive disease. 1
• This recommendation applies even though preoperative staging showed N0, as upstaging may occur after pathologic examination. 1

Critical Pitfalls to Avoid

• Do not omit preoperative radiotherapy for T3 tumors, as this significantly increases local recurrence risk. 1
• Do not add oxaliplatin to concurrent chemoradiotherapy, as it increases toxicity without benefit. 3
• Do not delay surgery beyond 12 weeks unless pursuing non-operative management for clinical complete response. 3
• Avoid injury to autonomic nerves during TME to preserve urinary and sexual function. 2
• Do not accept incomplete mesorectal excision, as this is the most important factor for preventing local recurrence. 2, 4

Expected Outcomes

• With appropriate preoperative chemoradiotherapy and TME, local recurrence rates should be <5-7% and 5-year disease-free survival approximately 75-80%. 1, 5, 6
• The pathologic complete response rate with long-course chemoradiotherapy is approximately 15-20%. 6