High Dose Proton Beam Therapy for Mucosal Malignant Melanoma of the Head and Neck

Abstract

To evaluate the efficacy and feasibility of primary tumor treatment by high dose proton beam therapy for patient with head and neck mucosal melanoma. Between April 2004 and October 2008, 21 patients with histologically confirmed head and neck mucosal melanoma underwent proton beam therapy. Seventeen patients had limited disease at the primary site and four patients had lymph node or distant metastasis. All patients were treated with 16 - 20 fractions of 3.5 GyE each for a total of 56 Gy to 70 GyE. PET fusion images were referred to define gross target volume in most cases (19/21) and others were defined the target only by CT or MRI. Concurrent chemotherapy was performed in 19 patients (90%) of the cohort. Furthermore, one to four courses of systemic chemotherapy were followed after proton beam therapy in nineteen patients. With a median follow-up time of 28 months (range 6-40 months), there was no recurrence at primary site. Regional recurrences at mucosal membrane in head and neck but out of gross target volume occurred in two patients at 12 months and 18 months after the treatment with 3-years locoregional progression free probability of 80%. Overall survivals were 68% at 1-year and 51% at 3-years after the treatment. Patients without metastatic disease had marginally better overall survival compared to those with metastatic disease (2-years OS. 74% vs. 50%). For those patients without metastasis disease free survival rate was 56% at 3-years. Patients with T1 disease had significantly better 2-years overall survival than those with T2-4 disease (100% vs. 57%, p =.037). Acute mild (grade 1 and 2) mucositis (11/21) and dermatitis (21/21) were frequently observed. Acute grade 3 mucositis and dermatitis were seen in one patient and in two patents, respectively. One patient reported to have bone necrosis at oral palate in CT examination but to maintain ordinary food intake. Neurological adverse effects were not seen at the time of this analysis. High dose proton beam therapy offers excellent local control for the patients with head and neck mucosal melanoma. Patients with early stage of the disease are expected to be subject of definitive proton beam therapy. The palliative therapy by proton beam can be applicable to avoid the progression of disease which may cause aerodigestive and sensory organ troubles. Further study is warranted to see long time outcome and to find the adaptive treatment under palliative setting.