What is abdominoperineal resection (APR) for rectal cancer in adults with low rectal tumors near the anal sphincter?

Abdominoperineal Resection (APR) for Rectal Cancer

What is APR?

APR is a radical surgical procedure involving en bloc resection of the rectosigmoid, rectum, anus, surrounding mesentery, mesorectum (via total mesorectal excision), and perianal soft tissue, which necessitates creation of a permanent end colostomy. 1

Indications for APR

APR should be performed when the tumor directly involves the anal sphincter or levator muscles, or when achieving a margin-negative resection would result in loss of anal sphincter function and incontinence. 1, 2

• For very low rectal tumors where sphincter preservation is not technically feasible, APR remains the appropriate surgical choice 3
• The procedure is also indicated for recurrent or persistent anal carcinoma after failed chemoradiotherapy 1

Surgical Technique

The procedure incorporates meticulous total mesorectal excision (TME), which involves sharp dissection to remove the mesorectum with associated vascular and lymphatic structures, fatty tissue, and mesorectal fascia as a complete "tumor package" while sparing autonomic nerves 1, 2

Technical Variations:

• Extralevator APR may offer benefits over conventional APR, including lower rates of intraoperative perforation, circumferential resection margin (CRM) involvement, and local recurrence, though results remain inconsistent across studies 1
• For anal cancer, APR may require wider lateral perianal margins than required for rectal cancer 1
• The procedure can be performed via open, laparoscopic, or robotic approaches with comparable oncological outcomes 2

Oncological Outcomes

Recent evidence suggests that worse outcomes historically attributed to APR are primarily due to tumor characteristics rather than the procedure itself:

• A 2017 propensity score-matched SEER analysis found that after optimal adjustment for patient characteristics, APR was not identified as a risk factor for cancer-specific mortality (HR = 0.85,95% CI: 0.56-1.29, P = 0.456) 4
• A 2024 study from the United States Rectal Cancer Consortium showed no significant difference in disease-free survival (HR = 0.90,95% CI: 0.53-1.52, P = 0.70) or overall survival (HR = 1.29,95% CI: 0.71-2.32, P = 0.39) between APR and low anterior resection for very-low rectal cancer 5

However, earlier retrospective data suggested patients with T3-T4 rectal cancer treated with APR had worse local control and overall survival compared to sphincter-preserving surgery 2

For anal carcinoma, 5-year survival rates of 39% to 66% have been observed following APR, with worse prognosis associated with node-positive disease at presentation and radiation doses <55 Gy 1

Quality of Life Considerations

Patients who undergo APR experience significantly worse body image, worse micturition symptoms, and less sexual enjoyment at 1-year post-surgery compared to those who have sphincter-preserving surgery. 1, 2, 3

• Despite these differences, long-term overall quality of life between patients with or without a permanent colostomy appears fairly comparable in some studies 2
• The permanent colostomy is a necessary consequence of the procedure and requires lifelong management 1, 3

Special Considerations

Wound Healing:

• For patients undergoing APR preceded by radiation therapy (particularly for anal cancer), closure of the perineal wound using rectus abdominis myocutaneous flap reconstruction results in decreased perineal wound complications 1
• Reconstructive tissue flaps for the perineum, such as vertical rectus or local myocutaneous flaps, should be considered 1

Postoperative Surveillance:

• Following APR, patients should undergo re-evaluation every 3-6 months for 5 years, including clinical evaluation and inguinal node palpation 1
• Annual chest, abdomen, and pelvis CT with contrast is recommended for 3 years 1

Common Pitfalls

• Avoid inadequate mesorectal excision: Ensure complete TME with intact mesorectal fascia to minimize local recurrence 2, 6
• Avoid nerve injury: Careful sharp dissection is essential to preserve autonomic nerves and maintain urinary and sexual function 1, 2
• Avoid inadequate margins: For anal cancer, ensure wider lateral perianal margins than typically required for rectal cancer 1
• Do not use intraoperative radiation therapy: This technique is not recommended during APR for recurrent anal cancer as it is unlikely to improve local control or survival 1