Utility of FDG-PET in clinical neuroendocrine prostate cancer

Fluorodeoxyglucose (FDG) positron emission tomography (PET) has well-characterized limitations in prostate adenocarcinoma (PCA). However, data assessing the utility of PET in neuroendocrine prostate cancer (NEPC) is limited to isolated case reports. Herein, we describe the first case series to assess the utility of FDG-PET in NEPC.

Inclusion criteria consisted of clinically progressive metastatic PCA in the setting of a chromogranin-A levels >1.5× the upper limit of normal, and ≥1 FDG-PET scan after the diagnosis of NEPC, which yielded 23 patients. All metastatic lesions on CT, PET, and bone scan were read by two independent physicians.

Five hundred ninety two unique lesions were identified across all imaging modalities, 510 were bone metastases, and 82 were soft tissue metastases. Of bone lesions, 22.2%, 92.7%, and 77.6% were detected by PET, CT, and bone scan, respectively. Of soft tissue lesions, 95.1% and 97.5% were detected by PET and CT, respectively. Stratified by the median survival from NEPC diagnosis, patients who survived <2.2 versus ≥2.2 years had more PET avid bone (8 vs. 2, P = 0.06) and soft tissue lesions (7 vs. 1, P = 0.01), and higher average SUVmax of bone (5.49 vs. 3.40, P = 0.04) and soft tissue lesions (8.02 vs. 3.90, P = 0.0002).

In patients with clinical NEPC, we demonstrate that FDG-PET has clinical utility in the detection of metastatic disease. In addition to detection, PET allows for treatment response to determine tumor viability. With novel therapies on the horizon to treat NEPC, consideration to investigate the use of FDG-PET to monitor response is warranted.