Novel nomogram combining depth of invasion and size can accurately predict the risk for regional nodal metastases for appendiceal neuroendocrine tumors (A-NET).

INTRODUCTION: The need for regional lymphadenectomy for treating appendiceal neuroendocrine tumors (A-NET) is determined by the risk of nodal metastasis. Current guidelines for A-NET are solely based on tumor size. Methods Patients with A-NET from 1988 to 2012 were identified from the SEER registry. The depth of invasion was defined as limited to the lamina propria (LP), invading the muscularis propria (MP), and through the serosa (TS). RESULTS: A total of 418 patients were included; the majority were female, white, and node-negative. On univariate and multivariable, the risk of nodal metastasis was associated with age, size, depth of invasion, and extent of surgery. The model predicted the likelihood of nodal metastasis, with an area under the curve of 0.89. On survival analysis, age and tumor size predicted the survival in A-NET. In a Cox regression model, they continued to predict survival. These data were utilized to create a nomogram to predict the risk of nodal metastases. CONCLUSION: This nomogram, accurately predicts the risk of regional nodal metastases in A-NET. In addition to providing valuable information on risk for regional nodal metastases, the depth of invasion is also predictive of survival for A-NET