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

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 (castration-resistant prostate cancer) and HSPC (hormone sensitive prostate cancer) 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.