This study aimed to evaluate the efficacy of
carbon-ion radiotherapy in combination with
chemotherapy using
dacarbazine,
nimustine, and
vincristine (DAV
therapy) in mucosal
melanoma. Twenty-one patients with clinically localized mucosal
melanoma of the head and neck were enrolled. The primary endpoint was 3-year overall survival (OS). Secondary endpoints included local control, progression-free survival (PFS), and adverse event occurrence.
Carbon-ion radiotherapy with a dose of 57.6-64.0 Gy (relative biological effectiveness) in 16 fractions was delivered concurrently with DAV
therapy, and 2 cycles of adjuvant DAV
therapy were administered every 6 weeks. The median follow-up periods were 15.5 months for all patients, and 31.2 months for 12 surviving patients. All patients had locally advanced T4a or T4b disease in the rhino-sinus area. In 16 patients (76.2%), 3 cycles of planned DAV
therapy were completed. The 3-year OS and PFS rates were 49.2% and 37.0% respectively. The 3-year local control rate was 92.3%. Eleven patients (52%) developed distant
metastasis, which was the most frequent pattern of the first failure. Commonly presenting acute grade 2-3 toxicities associated with
radiotherapy and
chemotherapy were
mucositis (11 patients [53%]) and
leukopenia (9 patients [43%]), which improved with
conservative therapy. None of the patients developed grade 3 or greater late toxicities.
Carbon-ion radiotherapy in combination with DAV
therapy led to excellent local control for advanced mucosal
melanoma within acceptable toxicities. The efficacy of additional DAV
therapy in improving survival was weaker than expected as distant
metastases still occurred frequently. Trial registration no. UMIN000007939.