PET/CT with ⁶⁸Ga-DOTA-TATE for Diagnosis of Neuroendocrine: Differentiation in Patients with Castrate-Resistant Prostate Cancer

Aim Castrate-resistant prostate cancer (CRPC) often shows histological evidence of neuroendocrine differentiation (NED). To evaluate the extent of NED in patients with CRPC, we used PET/CT with ⁶⁸Ga-[DOTA-Tyr³]-octreotate (⁶⁸Ga-DOTA-TATE), a somatostatin analog that binds somatostatin receptor 2 with high affinity. This radiotracer is used in imaging of neuroendocrine tumors. Methods Twelve patients (mean age, 65 [SD, 12] years) with CRPC were studied. Their mean prostate-specific antigen level at scanning was 85.6 (SD, 144.6) ng/mL. PET/CT images were obtained after the injection of 120 to 200 MBq of ⁶⁸Ga-DOTA-TATE. Results All participants had at least 1 blastic metastasis demonstrating uptake of ⁶⁸Ga-DOTA-TATE (mean SUVmax of 5.3 [SD, 2.3]). In 6 patients, moderately high to high uptakes (SUVmax, >5) were seen. Patients with multiple bone metastases had a significantly higher SUVmax compared with patients with few metastases (mean of 5.8 vs 3.8, P = 0.05). In 4 patients, lytic bone lesions or lymph node metastases also showed uptake of the tracer (mean SUVmax of 7.2 [SD, 3.2]). Uptake of the radiotracer was also observed in bones showing normal architecture in CT, suggesting that NED cells appear early during metastases development. Conclusions Uptake of ⁶⁸Ga-DOTA-TATE is a common finding in metastases of CRPC patients, suggesting that NED is frequent in these patients. In half of the patients, widespread uptake of ⁶⁸Ga-DOTA-TATE was observed. This suggests that the possibility of treating selected CRCP patients with anti-neuroendocrine tumor therapies should be explored and that ⁶⁸Ga-DOTA-TATE scanning could have a role in predicting the efficacy of these treatments.