Head and Neck Merkel Cell Carcinoma: Therapeutic Benefit of Adjuvant Radiotherapy for Nodal Disease.

Objectives: To evaluate the therapeutic effect of post‐operative radiotherapy (PORT) with respect to nodal status among patients with head and neck Merkel cell carcinoma (HNMCC). Methods: In this retrospective study, we queried Surveillance, Epidemiology, and End Results (SEER) dataset from 2000 through 2019. We included all adult patients who received primary surgical resection for histologically confirmed treatment naive HNMCC. Entropy balancing was used to reweight observations such that there was covariate balance between patients who received PORT and patients who received surgical resection alone. Doubly robust estimation was achieved by incorporating weights into a multivariable cox proportional hazards model. Planned post hoc subgroup analysis was performed to evaluate the impact of PORT by pathological node status. Results: Among 752 patients (mean age, 73.3 years [SD 10.8]; 64.2% male; 91.2% White; 41.9% node‐positive), 60.4% received PORT. Among node‐positive patients, we found that PORT was associated with improved overall survival (OS) (aHR, 0.55; 95% CI, 0.37–0.81; p = 0.003) and improved disease‐specific survival (DSS) (aHR, 0.57; 95% CI, 0.35–0.92; p = 0.022). Among node‐negative patients, we found that PORT was not associated with OS and was associated with worse DSS (aHR, 2.34; 95% CI, 1.30–4.23; p = 0.005). Conclusions: We found that PORT was associated with improved OS and DSS for node‐positive patients and worse DSS for node‐negative patients. For HNMCC treated with primary surgical resection, these data confirm the value of PORT for pathologically node‐positive patients and support the use of single modality surgical therapy for pathologically node‐negative patients without other adverse risk factors. Level of Evidence: 4 Laryngoscope, 134:3587–3594, 2024 [ABSTRACT FROM AUTHOR]