Post-operative radiation therapy is indicated for “low-risk” pathologic stage I Merkel cell carcinoma of the head and neck region but not for other locations

IntroductionThe role of post-operative radiation therapy (PORT) in early-stage Merkel cell carcinoma (MCC) is controversial. We analyzed the PORT preventing local recurrences (LR) among patients with low-risk, pathological stage I MCC based on location primary tumors: head/neck (HN) vs. non-head and neck (non-HN) sites.Materials/MethodsOne hundred forty-seven were identified that had “low risk” disease (pathological T1 tumor, negative microscopic margins, pathologic node status, no immunosuppression or prior systemic therapy). LR was defined as tumor recurrence within 2 cm surgical bed, its frequency estimated cumulative incidence method.ResultsSeventy-nine received (30 HN, 49 non-HN) a median dose 50 Gy (range: 8-64 Gy) while 68 treated surgery alone 38 non-HN). Overall, associated decreased risk (5-year rate: 9.5% 0%, p=0.004) 6 LRs observed group. While addition significantly reduced rates HN (21% p=0.034), non-HN managed alone. There significant difference MCC-specific survival comparing versus groups, without PORT.ConclusionsFor extremities trunk, excellent control achieved surgery, not indicated. However, reduction low-risk HN.