Lymph Node Positivity in T1/T2 Rectal Cancer: a Word of Caution in an Era of Increased Incidence and Changing Biology for Rectal Cancer.

Background: The evaluation of lymph nodes in rectal cancer dictates treatment. The goals of this study are to characterize the contemporary rate of lymph node metastasis in early stage rectal cancer and to re-investigate histologic factors that predict positive lymph nodes.
Materials and Methods: Using the National Cancer Database, we identified patients with clinical stage I rectal adenocarcinoma. Multivariable logistic regression was used to determine risk factors for lymph node positivity.
Results: 12.2% of patients with T1 tumors and 18.0% of patients with T2 tumors had positive lymph nodes. For T1 tumors, positive lymph nodes were present in 9.3% with neither poor differentiation nor lymphovascular invasion (LVI), 17.3% with poor differentiation alone, 34.7% with LVI alone, and 45.0% with both poor differentiation and LVI. For T2 tumors, positive lymph nodes were present in 11.7% with neither poor differentiation nor LVI, 25.3% with poor differentiation alone, 47.3% with LVI alone, and 41.5% with both poor differentiation and LVI. LVI was an independent predictor of positive lymph nodes (OR;4.75,95%CI;3.17-7.11,p < 0.001) for T1 and (OR;6.20,95%CI;4.53-8.51,p < 0.001) T2 tumors.
Conclusions: T1/T2 tumors have higher rates of positive lymph nodes when poor differentiation and LVI are present. These results should be taken into consideration prior to surgical treatment.