Backgrounds: Appendiceal cancers are usually diagnosed after appendectomy accidentally. The need for subsequent right hemicolectomy in these patients was determined by the potential risk of regional lymph node (LN) metastasis. Establishing a nomogram to forecast the potential risk of lymph node metastasis of appendiceal cancer could help in the next step of treatment.Methods: Patients with appendiceal cancer undergoing surgery was queried in the American cancer database of Surveillance, Epidemiology and End Results database from 2004 to 2016. A nomogram was established based on Logistic regression model.Results: Finally, 3,075 patients were diagnosed with appendectomy cancer from 2004 to 2016. Among them, there were 2028 (65.9%) cases with negative lymph nodes, 1047 (34.1%) cases with positive lymph nodes. Risk factors associated with lymph node metastasis include age, histological type, tissue grade, T stage, distant metastasis, and tumor size. We drew the ROC curves of the training group（0.754, P < 0.001） and the validation group （0.775, P < 0.001） respectively. C-index values of predictions were 0.772 (95%CI, 0.750-0.793) and 0.776 (95%CI, 0.746-0.807), and Brier score were 0.178 and 0.172 in training and validation group respectively. All of them showed excellent performance of the nomogram in our study.Conclusion: A new nomogram was created to assess the potential risk of LN metastasis in patients of appendiceal cancer by utilizing age, tumor histology, tumor pathologic grade, tumor size, T-stage, and M-stage. The nomogram could provide a strong reference for the right hemicolectomy and facilitate clinic decision.
Keywords: Appendiceal cancer; metastases; nodal metastases; nomogram; right hemicolectomy; surveillance epidemiology and end results database.