Predictive value of 3\u27-deoxy-3\u27-[18F]fluorothymidine positron emission tomography/computed tomography for outcome of carbon ion radiotherapy in patients with head and neck mucosal malignant melanoma

Abstract

Aim: In this prospective clinical study, we assessed the predictive value of 3\u27-deoxy-3\u27-[18F]fluorothymidine (FLT) positron emission tomography/computed tomography (PET/CT) for the outcome of carbon ion radiotherapy (CIRT) in patients with mucosal malignant melanoma (MMM) of the head and neck.Materials & Methods: Thirteen patients (69 +- 13 years) with histologically-proven MMM tumor were enrolled. CIRT was performed with a total dose of 57.6&#8211;64.0 gray equivalents per 16 fractions over a period of 4 weeks. FLT-PET/CT was performed before and again 1 month after CIRT. Tumor FLT uptake was quantitatively assessed using the maximum standardized uptake value (SUVmax). FLT-PET parameters (pre-CIRT SUVmax, post-CIRT SUVmax, and the reduction rate [RR]) and clinical parameters (age, gender, tumor site, tumor status, gross tumor volume [GTV], regional lymph node involvement and primary response) were evaluated in relation to survival estimates. The follow-up period was 36.7 +- 7.9 months for 4 survivors, and 16.1 +- 5.9 months for 9 deceased patients.Results: Pre-CIRT SUVmax of &#8805; 4.3, age of &#8805; 80-years-old, sinonasal cavity tumor site, and GTV of &#8805; 39-mL were found to be statistically significant prognostic factors for better overall survival. Pre-CIRT SUVmax of &#8805; 5.0, age of &#8805; 80-years-old, sinonasal cavity tumor site, and the absence of regional lymph node involvement were significant prognostic factors for better metastasis-free survival. RR of &#8805; 35% and GTV of < 73-mL were predictive of better local control.Conclusion: Our investigation suggests that FLT-PET/CT may be useful for predicting outcome of CIRT in patients with MMM of the head and neck. These results will contribute to the establishment of an effective staging system for MMM based on prognostic factors, depending on patient selection and treatment choice.Annual Congress of the European Association of Nuclear Medicin