Optimal adjuvant radiotherapy dose for stage I, II or III Merkel cell carcinoma: an analysis of the National Cancer Database.

Academic Article

Abstract

  • BACKGROUND: We performed an analysis of the National Cancer Database to determine optimal doses of conventionally-fractionated adjuvant radiotherapy for patients with stage I/II or III Merkel cell carcinoma. METHODS: The cohort included 2735 patients with resected Merkel cell carcinoma of the head and neck, trunk or extremities receiving radiotherapy. Exclusion criteria included doses of radiotherapy <30 or >80 Gy, or dose per fraction >200 or <180 cGy. Recursive partitioning analysis and spline models were used to select dose thresholds. Multivariable Cox regression was performed to validate thresholds with respect to overall survival. RESULTS: Recursive partitioning analysis models defined a threshold of 57 Gy for stage I/II Merkel cell carcinoma, above which 3-year overall survival rate was decreased (P < 0.0001). The 3-year overall survival rate for patients receiving 50.0-57.0 Gy (81.2%) was greater compared to doses of 30.0-49.9 Gy (75.3%) or >57.0 Gy (70%, P < 0.0001). Doses > 57.0 Gy were associated with an increased hazard of death (1.31, confidence interval 1.07-1.60) with respect to doses of 50.0-57.0 Gy. Doses < 50.0 Gy for stage III Merkel cell carcinoma were associated with worsened 3-year overall survival (P < 0.0001) and increased hazard of death (2.01, confidence interval 1.43-2.82) with respect to doses between 50.0 and 57.0 Gy. CONCLUSIONS: Our results support doses of 50-57 Gy for most patients with stage I/II Merkel cell carcinoma receiving conventionally-fractionated adjuvant radiotherapy. In contrast to a prior National Cancer Database analysis, our results suggest doses ≥ 50 Gy should be strongly considered for patients with stage III Merkel cell carcinoma regardless of anatomic subsite.

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    Keywords

  • Merkel cell carcinoma, dose, optimal dose, radiation, radiotherapy, Adult, Aged, Aged, 80 and over, Carcinoma, Merkel Cell, Databases, Factual, Dose-Response Relationship, Radiation, Female, Humans, Male, Middle Aged, Radiotherapy Dosage, Radiotherapy, Adjuvant, Skin Neoplasms, Survival Analysis, Survival Rate, United States

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    Author List

  • Yusuf M; Gaskins J; Wall W; Tennant P; Bumpous J; Dunlap N

    • Start Page

  • 175

    • End Page

  • 184

    • Volume

  • 50

    • Issue

  • 2