The utilities of functional images for predicting the prognosis of mucosal malignant melanoma before heavy ion radiotherapy

The Purpose of this study was to evaluate the potential of apparent diffusion coefficient (ADC) value before carbon ion radiotherapy for mucosal malignant melanoma to predict the prognosis. We recruited patients with mucosal malignant melanoma of the head and neck who were treated by carbon ion radiotherapy with concomitant chemotherapy, and analyzed retrospectively. All patients were performed carbon ion radiotherapy with 57.6 GyE/16 fr. with concurrent chemotherapy (DAV). Distant metastasis-free survival rate and overall survival were calculated with Kaplan-Meier method. Thirty-seven patients were enrolled. Median follow-up period was 19.3 months. The 3-year distant metastasis-free survival rate and overall survival rate of all patients were 40.7% and 81.2%, respectively. Distant metastasis-free survival rate and overall survival rate of the patients with lower minimum ADC were significant worse than those of the patients with higher minimum ADC (log-rank test, p=0.004 and p=0.02, respectively). Minimum ADC might be a prognostic factor of distant metastasis and overall survival of mucosal malignant melanoma of the head and neck. (author)