Predictors and outcomes of positive surgical margins after local excision of clinical T1 rectal cancer: A National Cancer Database analysis

Abstract

Background: Transanal local excision and the use of specialized platforms has become increasingly popular for early-stage rectal cancer. Predictors and outcomes of positive resection margins following transanal local excision for early-stage rectal cancer have yet to be explored.

Methods: This was a retrospective analysis of the National Cancer Database of all patients with clinical nonmetastatic node negative T1 rectal adenocarcinoma who underwent transanal local excision from 2004 to 2017. Patients with positive surgical margins were compared to those with negative resection margins to determine factors associated with predictors and outcomes of positive surgical margins after transanal local excision. The main outcome measure was overall survival.

Results: Of 318,548 patients with rectal adenocarcinoma in the National Cancer Database, 9,078 (2.8%) met the inclusion criteria. The positive surgical margins rate was 7.4%. Predictors of positive surgical margins were older age (odds ratio, 1.03; P < .001), higher Charlson comorbidity index (odds ratio, 1.24; P = .004), poorly differentiated carcinomas (odds ratio, 1.89; P < .001), mucinous (odds ratio, 2.36; P = .003) and signet-ring cell carcinomas (odds ratio, 4.7; P = .048). Independent predictors of reduced survival were older age (hazard ratio, 1.062; P < .001), male sex (hazard ratio, 1.214; P = .011), Charlson comorbidity index 3 (hazard ratio, 1.94; P < .001), pathologic T2 (hazard ratio, 1.27; P = .036) and T3 stages (hazard ratio, 1.77; P = .006), poorly differentiated carcinomas (hazard ratio, 1.47; P = .008), and positive surgical margins (hazard ratio, 1.374; P = .018). The positive surgical margins group's median overall survival was significantly shorter (88 vs 159.3 months, P < .001).

Conclusion: Positive surgical margins after transanal local excision for early-stage node-negative rectal cancer adversely affects prognosis. Older male patients with higher Charlson comorbidity index scores and poorly differentiated mucinous or signet cell histology tumors are at risk for positive surgical margins. Patient selection according to these suggested criteria may help avoid positive surgical margins.