Day RW, Chang YH, Stucky CC, et al. - Researchers sought to develop a predictive model that would help direct subsequent surgical therapy in histologic subtypes of appendiceal cancer, which vary in their propensity for metastases to regional lymph nodes (LN). From the National Cancer Database, they identified a total of 21,647 patients, comprising of 9,079 (41.9%) with node negative disease, 4,575 (21.1%) with node positive disease, and 7,993 (36.9%) with unknown LN status. Following were identified as the strongest predictors of LN positivity: histology (carcinoid tumors OR 12.78, 95% CI 9.01–18.12), increasing T Stage (T3 OR 3.36, 95% CI 2.52–4.50, T4 OR 6.30, 95% CI 4.71–8.42), and tumor grade (G3 OR 5.55, 95% CI 4.78–6.45, G4 OR 5.98, 95% CI 4.30–8.31). A calculator was developed using the coefficients from the regression analysis that generated predicted probabilities of LN metastases given certain inputs. Overall findings suggest the possibility for quantification of the risk for nodal metastases in patients with appendiceal cancers with reasonable accuracy using a predictive model incorporating patient age, gender, tumor histology, T-stage, and grade. This model can help inform clinical decision making concerning the necessity for a right hemicolectomy following appendectomy.