Curative carbon ion radiotherapy in a head and neck mucosal melanoma series: Facing the future within multidisciplinarity.

Purpose: To evaluate efficacy and toxicity of carbon ion radiotherapy (CIRT) in locally advanced head and neck mucosal melanoma (HNMM) patients treated at our Institute.
Materials and Methods: Between June 2013 and June 2020, 40 HNMM patients were treated with CIRT. Prescription dose was 65.6-68.8 Gy relative biological effectiveness [RBE] in 16 fractions. Twelve (30%) patients received only biopsy, 28 (70%) surgical resection before CIRT. Immunotherapy was administered before and/or after CIRT in 45% of patients, mainly for distant progression (89%).
Results: Median follow-up was 18 months. 2-year Local Relapse Free Survival (LRFS), Overall Survival (OS), Progression Free Survival (PFS) and Distant Metastasis Free Survival (DMFS) were 84.5%, 58.6%, 33.2% and 37.3%, respectively. At univariate analysis, LRFS was significantly better for non-recurrent status, < 2 surgeries before CIRT and treatment started < 9 months from the initial diagnosis, with no significant differences for operated versus unresected patients. After relapse, immunotherapy provided longer median OS (17 months vs 3.6, p-value<0.001). Late toxicity ≥ G3 (graded with CTCAE 5.0 scale) was reported in 10% of patients.
Conclusion: CIRT in advanced HNMM patients is safe and locally effective. Prospective trials are warranted to assess the role of targeted/immune- systemic therapy to improve OS.
Competing Interests: Declaration of Competing Interest Sara Ronchi, Alessandro Cicchetti, Maria Bonora, Rossana Ingargiola, Anna Maria Camarda, Stefania Russo,Sara Imparato, Paolo Castelnuovo, Ernesto Pasquini, Piero Nicolai, Mohssen Ansarin, Marco Benazzo, EsterOrlandi and Barbara Vischioni declare no conflict of interest. Michele Del Vecchio reports research funding to their institution for clinical studies and research outside the submitted work from MSD, and as a consultant or advisor from BMS, MSD, Novartis, Pierre Fabre, Immunocore.
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