Abdominoperineal resection and low anterior resection: comparison of long-term oncologic outcome in matched patients with lower rectal cancer.

PURPOSE: The current study aimed to compare the oncologic outcome and pattern of metastasis after abdominoperineal resection (APR) and low anterior resection (LAR) treating lower rectal cancer.
METHODS: A total of 804 patients undergoing curative resection (R0) were enrolled prospectively. The APR and LAR groups (n = 402, respectively) were matched for gender, age, and stage, for a retrospectively comparative analysis.
RESULTS: In a multivariate analysis with potential variables, APR itself was not a risk factor for increased local recurrence (LR) or reduced survival (P = 0.243-0.994). Circumferential resection margin (CRM) involvement as an operation-related risk was 1.6-fold more frequent in the APR group and was significantly associated with LR and systemic recurrence (OR, 2.487-4.017; P < 0.01). Circumferential margin positivity (CRM+) was concurrently correlated with advanced stage, larger tumor (long diameter, >4 cm), and longer sagittal midpelvic diameter (>10 cm) in a multivariate analysis (P < 0.001-0.05). The site of metastasis did not differ between the two groups, with the exception of lung metastasis which was more frequent in the APR group (APR vs. LAR: 15.9 vs. 10 %, P = 0.015). In the APR group, CRM+ and the presence of an infiltrating tumor were correlated with disease-free survival (hazard ratio (HR), 1.644 and 1.654, respectively), whereas elevated serum carcinoembryonic antigen and LVI+ were correlated with overall survival (HR, 1.57 and 1.671, respectively), in a multivariate analysis with potential variables (P < 0.05).
CONCLUSIONS: When performed with appropriate skill to achieve R0 resection, APR can be used safely without impairing oncological outcome, although sphincter-preserving surgery should remain the preferred option.