Metastasis-directed Therapy (SBRT) Guided by PET-CT 18F-CHOLINE Versus PET-CT 68Ga-PSMA in Castration-sensitive Oligorecurrent Prostate Cancer: A Comparative Analysis of Effectiveness

Abstract

Background: The present analysis aims to compare the impact of 18F-fluorocholine (¹⁸F-choline) and gallium-68 prostate-specific membrane antigen (⁶⁸Ga-PSMA) positron emission tomography (PET)-computed tomography (CT)-guided metastases-directed therapies (MDTs) in patients with castration-sensitive oligorecurrent prostate cancer (PC).

Materials and methods: Inclusion criteria were: (1) histologically proven prostate adenocarcinoma; (2) evidence of biochemical relapse after primary tumor treatment; (3) ≤ 3 hypermetabolic oligorecurrent lesions detected by ¹⁸F-choline or ⁶⁸Ga-PSMA PET-CT; (4) PET-CT imaging performed in a single nuclear medicine department; (5) patients treated with upfront stereotactic body radiotherapy (SBRT) without hormone therapy; and (6) SBRT delivered with a dose per fraction ≥ 5 Gy. In the case of oligoprogression (≤ 3 lesions outside the previous RT field) after MTD, a further course of SBRT was proposed; otherwise, androgen deprivation therapy (ADT) was administered.

Results: A total of 118 lesions in 88 patients were analyzed. Forty-four (50%) patients underwent ⁶⁸Ga-PSMA PET-guided SBRT, and the remaining underwent choline PET-based SBRT. The median follow-up was 25 months (range, 5-87 months) for the entire cohort. Overall survival and local control were both 100%. Distant progression occurred in 48 (54.5%) patients, for a median distant progression-free survival of 22.8 months (range, 14.4-28.8 months). The median pre-SBRT prostate-specific antigen was 2.04 ng/mL in the choline PET cohort and 0.58 ng/mL in the PSMA-PET arm. Disease-free survival rates were 63.6% and 34%, respectively, in the ⁶⁸Ga-PSMA and choline PET group (P = .06). The ADT administration rate was higher after choline-PET-guided SBRT (P = .00) owing to the higher incidence of polymetastatic disease after first-course SBRT compared with ⁶⁸Ga-PSMA-based SBRT.

Conclusion: In the setting of oligorecurrent castration-sensitive PC, PSMA-PET-guided SBRT produced a higher rate of ADT-free patients when compared with the ¹⁸F-choline-PET cohort. Randomized trials are advocated.

Keywords: Metastasis-directed therapy; Oligometastases; PSMA-PET; Prostate cancer; Stereotactic body radiation therapy.