Second cancers discovered by ¹⁸FDG PET/CT imaging for choroidal melanoma

Background: Positron-emission tomography/computed tomography (PET/CT) is a unique imaging tool that aids in the detection of cancerous lesions. It is currently and widely used for cancer staging (both initial and follow-up). Here we report our findings of second primary cancers incidentally discovered during PET/CT staging of patients with choroidal melanomas. Methods: We performed a retrospective case review of 139 patients with uveal melanoma who were subsequently evaluated by whole-body [18-fluorine-labeled] 2-deoxy-2-fluoro-D-glucose (¹⁸FDG) PET/CT imaging. In this series, 93 were scanned before treatment and 46 during the course of their follow-up systemic examinations. Their mean follow-up was 50.9 months. Results: Six patients (4.3%) had second primary cancers revealed by PET/CT imaging. Three patients (50%) were synchronous (found at initial staging), and the remaining 3 patients (50%) were metachronous (found at follow-up staging). Second primary cancers were found in the lung, breast, uterus, colon, and thyroid. Conclusions: Although whole-body PET/CT scans were ordered as part of the staging process of patients with diagnosed choroidal melanoma, both synchronous and metachronous second primary cancers were found. PET/CT has become an indispensable tool for staging, diagnosis, and treatment planning for choroidal melanoma. The possibility of detecting second primary cancers should also be considered valuable.