[Effects of tumor distance from anal verge and types of operations on survival outcomes for low rectal cancer after neoadjuvant chemoradiotherapy].

OBJECTIVE: To assess the effects of neoadjuvant chemoradiotherapy on survival outcomes of low rectal cancer after sphincter-preserving or removing surgery.

METHODS: A total of 135 patients with rectal cancer within 10 cm from anal verge after neoadjuvant chemoradiotherapy were enrolled into this retrospective study from 2005 to 2012 at a single institute. There were 79 males and 56 females with a mean age of (58 ± 12) years and an average distance of (5.2 ± 2.1) cm from anal verge. The effects of gender, age, distance of tumor from anal verge, surgical procedure, T-stage downstaging, lateral resection margin and post-treatment lymphatic node status on 3-year disease-free survival (DFS) were examined.

RESULTS: The overall 3-year DFS was 85.2% (115/135). Among 95 sphincter-preserving operations, there were anterior resection (n = 79), anterior perineal plane for ultra low anterior resection (APPEAR) technique (n = 12), Hartmann procedure (n = 3) and Parks procedure (n = 1). Among 40 sphincter-removing operations, there were abdominoperineal resection (APR) procedure (n = 39) and intersphincteric resection(ISR) (n = 1). The survival of patients undergoing sphincter-preserving or removing procedures did not differ in 3-year DFS (85.3% (81/95) vs 85.0% (34/40) , χ(2) = 0.000, P = 0.985) . Lateral resection margin and post-treatment lymphatic node status significantly affected DFS. The differential level from anal verge showed a trend of close relationship to 3-year DFS (81.5% (22/27) for 2-3 cm, 82.5% (47/57) for 4-5 cm vs 95.1% (39/41) for 6-7 cm), but without statistic significance (χ(2) = 3.111, 3.522; P = 0.078, 0.061). The survival rate for patients with sphincter-preserving at 6-7 cm from anal verge was significantly higher than that at 4-5 cm (95.0% (38/40) vs 79.5% (31/39) ,χ(2) = 4.227, P = 0.039) , but showed no differences to that with sphincter-removing at 2-3 cm from anal verge (81.0% (17/21),χ(2) = 2.864, P = 0.091) . The multivariate analysis showed that post-treatment lymphatic node status was the only prognostic factor to 3-year DFS (Wald = 4.454, P = 0.035) .

CONCLUSIONS: Lateral resection margin and post-treatment lymphatic node status play an important role on DFS for patients with low rectal cancer after neoadjuvant chemoradiotherapy. The distance from anal verge is correlated with 3-year disease-free survival. Patients with tumor at 4-5 cm from annal verge can not benefit for survival when they get sphincter-preserving operations.