Partial mesorectal excision can be a primary option for middle rectal cancer: a propensity score-matched retrospective analysis

Purpose: Although partial mesorectal excision (PME) and total mesorectal excision (TME) is primarily indicated for the upper and lower rectal cancer, respectively, few studies have evaluated whether PME or TME is more optimal for middle rectal cancer. Methods: This study included 671 patients with middle and upper rectal cancer who underwent robot-assisted PME or TME. The 2 groups were optimized by propensity score matching of sex, age, clinical stage, tumor location, and neoadjuvant treatment. Results: Complete mesorectal excision was achieved in 617 of 671 patients (92.0%), without showing a difference between the PME and TME groups. Local recurrence rate (5.3% vs. 4.3%, P> 0.999) and systemic recurrence rate (8.5% vs. 16.0%, P = 0.181) also did not differ between the 2 groups, in patients with middle and upper rectal cancer. The 5-year disease-free survival (81.4% vs. 74.0%, P = 0.537) and overall survival (88.0% vs. 81.1%, P = 0.847) also did not differ between the PME and TME groups, confined to middle rectal cancer. Moreover, 5-year recurrence and survival rates were not affected by distal resection margins of 2 cm (P = 0.112) to 4 cm (P > 0.999), regardless of pathological stages. Postoperative complication rate was higher in the TME than in the PME group (21.4% vs. 14.5%, P = 0.027). Incontinence was independently associated with TME (odds ratio [OR], 2.009; 95% confidence interval, 1.015-3.975; P = 0.045), along with older age (OR, 4.366, P < 0.001) and prolonged operation time (OR, 2.196; P = 0.500). Conclusion: PME can be primarily recommended for patients with middle rectal cancer with lower margin of > 5 cm from the anal verge.