"Utility of PET/CT with [18F] F-fluorocholine in assessing the response to antiandrogenic therapy in patients with prostate cancer."

Abstract

Objective: To evaluate the correlation between response assessment measured by PET/CT with [¹⁸F] F-fluorocholine (Choline PET/CT) and serum levels of PSA in patients with prostate cancer under antiandrogenic treatment.

Methodology: A retrospective study included patients with CRPC and CSPC treated with enzalutamide, abiraterone, or apalutamide between June 2018 and July 2021, who underwent baseline and a follow-up Choline PET/CT. The difference in maximum SUVmax (ΔSUV) between both studies and the PSA value before and at follow-up were recorded. The response to treatment was compared by PSA vs. PET, assessing their association, agreement, and correlation.

Results: Thirty patients were included (median age 74 years, range 68-78), 12 with CSPC and 18 with CRPC; 22 had nodal disease, and 15 had active bone disease. The average time between pre-treatment and follow-up PET/CT was 11 months (range 3.5-23). Patients with extra-nodal metastatic disease at the beginning of treatment showed a higher correlation between PSA and ΔSUV (OR 4.375). In patients with bone disease at the start of treatment, 80% were classified as non-responders on PET response assessment, while only 40% were non-responders by PSA. The correlation between PET and PSA was mild (Kendall's tau_b 0.26), and the classification into Responders/Non-responders had only slight agreement (Cohen's kappa 0.30).

Conclusion: Choline PET/CT shows low concordance with the PSA values obtained during the follow-up of response to anti-androgen therapy, especially in patients with bone involvement.