Depth of Tumor Invasion Independently Predicts Lymph Node Metastasis in T2 Rectal Cancer

The aim of this study was to identify risk factors of lymph node metastasis (LNM) for T2 rectal cancer. From a prospectively maintained single-institution database, we identified 346 consecutive pT2 rectal cancers treated with total mesorectal excision from 1998 to 2009. Univariate and multivariate analyses were performed to identify risk factors associated with overall and intermediate/apical LNM. The incidence of overall and intermediate/apical LNM was analyzed by tree analysis. Age, tumor location, pathological features, and depth of invasion were independent predictors for overall LNM. Tumor location, pathological features, and depth of invasion were independent predictors for intermediate/apical LNM. Tree analysis showed that the incidence of LNM was 7.7% for upper rectal cancer with favorable pathological features, and 3.4% for mid/lower rectal cancer without other identified risk factors. The incidence of intermediate/apical LNM was 5.7% for superficial T2 rectal cancer with favorable pathological features, and 3.1% for deep T2 rectal cancer locating in upper rectum with favorable pathological features. Depth of invasion is an independent predictor for LNM in T2 rectal cancer. Using tree analysis, we identified a subset of patients with low risk of LNM who may be candidates of local excision.