The role of adjuvant therapy in the management of head and neck merkel cell carcinoma: an analysis of 4815 patients.

IMPORTANCE: Merkel cell carcinoma (MCC) is a rare neuroendocrine malignant neoplasm that most commonly occurs in the head and neck and is rapidly increasing in incidence. The role of adjuvant chemoradiotherapy (CRT) in the management of head and neck MCC remains controversial.

OBJECTIVE: To evaluate the association between different adjuvant therapies and survival in head and neck MCC.

DESIGN, SETTING, AND PARTICIPANTS: Retrospective review of adult patients with head and neck MCC who had surgery recorded in the National Cancer Data Base from 1998 to 2011.

INTERVENTIONS: Surgical excision, adjuvant radiation therapy (RT), or adjuvant CRT.

MAIN OUTCOMES AND MEASURES: Our main outcome was overall survival (OS). Statistical analysis included χ2, t tests, Kaplan-Meier survival analysis, and Cox proportional hazards regression analysis.

RESULTS: We identified 4815 patients; 92.0% underwent standard surgical excision, and 8.0% underwent Mohs surgery. On multivariate analysis, age at least 75 years (hazard ratio [HR], 2.83 [95% CI, 1.82-4.41]), larger tumor size, positive margins (HR, 1.52 [95% CI, 1.25-1.85]), and metastatic lymph nodes (HR, 2.29 [95% CI, 1.84-2.85]) were independently associated with decreased OS. Postoperative CRT (HR, 0.62 [95% CI, 0.47-0.81]) and RT (HR, 0.80 [95% CI, 0.70-0.92]) provided a survival benefit over surgery alone. Adjuvant CRT was associated with improved OS over adjuvant RT in patients with positive margins (HR, 0.48 [95% CI, 0.25-0.93]), tumor size at least 3 cm (HR, 0.52 [95% CI, 0.30-0.90]), and male sex (HR, 0.69 [95% CI, 0.50-0.94]).

CONCLUSIONS AND RELEVANCE: To our knowledge, this the first study examining the role of adjuvant CRT in head and neck MCC. Results suggest that adjuvant CRT may help improve survival in high-risk patients, such as males and those with positive margins and larger tumors.