Background: Laparoscopic sphincter preservation for low rectal cancer is challenging because of the high risk of positive circumferential resection margin. We hypothesized that perineal dissection of the distal rectum may improve quality of surgery, compared with the conventional abdominal dissection.
Methods: Between 2008 and 2012, 100 patients with low rectal cancer (< 6 cm from the anal verge) suitable for sphincter preservation were randomized between perineal and abdominal low rectal dissection. Surgery included laparoscopic mobilization of the left colon with high rectal dissection. Distal rectal dissection was performed laparoscopically in the abdominal group and transanally in the perineal group. The primary endpoint was quality of surgery (circumferential resection margin, mesorectum grade, and lymph nodes). Secondary end points were morbidity and conversion.
Results: The rate of positive circumferential resection margin decreased significantly after perineal compared with abdominal low rectal dissection, 4% versus 18% (P = 0.025). The mesorectum grade and the number of lymph nodes analyzed did not differ between the 2 groups. There was no difference in surgical morbidity (12% vs 14%; P = 0.766) and conversion (4% vs 10%; P = 0.436) between perineal and abdominal rectal dissection. Multivariate analysis showed that abdominal rectal dissection was the only independent factor of positive circumferential resection margin (odds ratio = 5.25; 95% confidence interval: 1.03-26.70; P = 0.046).
Conclusions: Perineal rectal dissection reduces the risk of positive circumferential resection margin, as compared with the conventional abdominal dissection in low rectal cancer. This suggests the perineal rectal dissection as a new standard in laparoscopic sphincter-saving resection for low rectal cancer.