Abstract
Purpose: :
Positive metabolic activity measured by PET/CT has been correlated as a poor prognostic factor for uveal melanoma. Faster tumor regression after radiotherapy has been associated with increased patient mortality. We investigated the relationship of positive metabolic activity by PET/CT with initial regression of uveal melanoma after plaque radiotherapy and thermotherapy.
Methods: :
Twenty seven patients with uveal melanoma who underwent pretreatment whole-body PET/CT and received RU-106 plaque radiotherapy and thermotherapy between 2006 and 2011 were included. Metabolic activity of uveal melanoma measured as standardized uptake value (SUV) by PET/CT was evaluated with respect to the tumor regression rates.
Results: :
Before treatment, the median tumor thickness was 8.8mm for tumors with positive metabolic activity (group 1, 7 patients) and 5.5mm for those with negative metabolic activity (group 2, 20 patients). The median tumor thickness in percentage with respect to original thickness at 4, 8, 12 months after treatment were 88%, 78%, 66% for group 1 and 95%, 88%, 81% for group 2. The median monthly tumor regression rate was 2.9% for group 1 and 1.2% for group 2. The percent decrease in tumor thickness and month tumor regression rate of group 1 (12%, 3.1%, respectively) was significantly higher than those of group 2 (5%, 1.3%, respectively) at 4 months after treatment (P=0.022). Two patients (29%) in group 1 developed metastatic disease 2 years after treatments, whereas no patient in group 2 developed metastatic disease.
Conclusions: :
Positive metabolic activity measured by PET/CT was associated with greater initial regression of uveal melanoma after Ru-106 plaque radiotherapy and thermotherapy.
Keywords: melanoma • tumors • uvea