A multi-institutional retrospective study was performed in northern Japan to analyze the outcome of external radiotherapy as the definitive treatment modality for localized mucosal melanoma of the head and neck.
Thirty-one patients with localized mucosal melanoma of the head and neck treated by external radiotherapy at nine institutions of the Northern Japan Radiation Therapy Oncology Group between 1980 and 1999 were enrolled in this study. Radiotherapy alone was performed in 21 patients, and the remaining 10 patients received postoperative radiotherapy for gross residual tumors. The fraction size of radiotherapy varied from 1.5-13.8 Gy, with the total dose ranging from 32-64 Gy (median, 50 Gy). The follow-up periods ranged from 1-214 months (median, 16 months).
Complete or partial responses were observed in 9 patients (29%) and 18 patients (58%), respectively. Local recurrence occurred in 13 patients (41.9%) and distant metastasis occurred in 11 patients (35.5%). Most incidences of local recurrence and distant metastasis developed within 2 years after the initial treatment. Overall cause-specific survival rates of patients at 1 and 3 years were 73% and 33%, respectively. Univariate analysis showed that high dose per fractionated radiotherapy doses (>or=3 Gy) was associated with better prognosis for both local control (p = 0.048) and survival (p = 0.045). Multivariate analysis indicated that age (better prognosis in younger patients, p = 0.046) was the only significant factor. Radiotherapy for gross residual lesions after surgery did not seem to impact the significant gain of local control and survival. We observed two fatal late complications of mucosal ulcer and bleeding in the high dose per fractionated radiotherapy group.
Radiotherapy at a dose of 3 Gy or more per fraction was effective in gaining local control in patients with localized mucosal melanoma of the head and neck, and subsequently better survival was possible, especially in younger patients.