Postoperative Radiotherapy for Head and Neck Merkel Cell Carcinoma: Sometimes, Less Is More.

Abstract

Head and neck Merkel cell carcinoma (HNMCC) is a rare but aggressive malignancy characterized by high recurrence rates and an uncertain survival benefit from postoperative radiotherapy (PORT). This study aimed to develop and validate a prognostic nomogram for risk stratification and to evaluate the survival benefit of PORT across risk groups. Patients with surgically resected, non-metastatic HNMCC were retrospectively identified. Independent prognostic factors for overall survival (OS) were identified via univariate and multivariate Cox regression. A nomogram was constructed and internally validated using time-dependent receiver operating characteristic curves, calibration plots, and decision curve analysis (DCA). Patients were stratified into high- and low-risk groups based on nomogram scores, and the impact of PORT was assessed within each risk category using Kaplan-Meier analysis and log-rank tests. A total of 1776 patients were included. Six variables-age, sex, marital status, race, T stage, and N stage-were independently associated with OS and used to construct the nomogram. The model demonstrated superior discriminative ability and calibration performance compared to traditional staging systems, and DCA confirmed improved clinical utility. Among high-risk patients, PORT significantly improved 5- and 10-year OS (p < 0.001), whereas no significant survival benefit was observed in the low-risk group (p > 0.05). This study presents a validated nomogram that accurately predicts survival and supports risk-adapted use of PORT in HNMCC. Selective application of PORT based on individualized risk may optimize outcomes while minimizing overtreatment.