Predictors of outcome following local excision for T1 rectal adenocarcinoma: A contemporary analysis.
35 Background: Local excision (LE) alone is a standard treatment option for appropriately selected early stage rectal adenocarcinoma patients. Guidelines for this therapeutic approach are based upon retrospective single institution data, some of which dates back 30 years. We thus sought to use the National Cancer Database (NCDB) to examine outcomes in a large cohort of patients with early stage rectal adenocarcinoma treated with LE and to identify/confirm predictors of outcome. Methods: We queried the NCDB for patients with pT1N0M0 rectal adenocarcinoma treated with local excision alone. Baseline characteristics were tabulated and included lymphovascular invasion (LVI), perineural invasion (PNI), grade, and size all of which have been recorded in the NCDB since 2010. Multivariable Cox regression was used to identify predictors of overall survival. Kaplan Meier curves were generated to compare survival based upon significant factors found on multivariable analysis. Results: Using the above criteria, we identified 887 patients eligible for analysis across 2010-2014. The median age was 67 and 57% of patients were male. The median tumor size was 1.5 cm (IQ range: 0.9-2.5 cm). A minority of patients had grade 3 tumors (5%), LVI (8%), or PNI ( < 1%). Median follow up was 36 months (1-83). On multivariable Cox regression, predictors of worse survival included: size > 4 cm, age > 67, higher comorbidity score, and presence of LVI. On Kaplan Meier analysis, 5 year OS was 75% vs. 74% for patients without and with LVI, respectively (p = 0.0115). In terms of size, the 5 year OS was 74% vs. 51%for size < 4cm and size > 4cm (p = 0.0138). Conclusions: Our large contemporary series demonstrates excellent survival outcomes in patients with early stage rectal adenocarcinoma treated with LE alone. LVI remains a predictor of outcome, while grade and perineural invasion were not significant in this analysis. This finding is likely due to a small number of patients with those characteristics.