68Ga-PSMA PET/CT After Radical Therapy for Patients With Early Relapsed Prostate Cancer

By Emily Menendez - Last Updated: November 29, 2022

A recent study published in Scientific Reports analyzed the effectiveness of 68Ga-PSMA positron emission tomography/computed tomography (PET/CT) in detecting the presence of local or systemic disease in patients with prostate cancer (PCa) and a history of biochemical recurrence (BCR).

BCR occurs when prostate-specific antigen (PSA) levels rise in patients with PCa after they have had surgery or received radiation treatment. BCR is estimated to affect 25% of patients treated with radical prostatectomy (RP) and 45% of patients treated with external beam radiotherapy (RT).

A total of 52 patients with PCa and BCR were enrolled in the study that took place between November 2017 and December 2019. The median age of the patients was 71.3 years. Performance of prostate-specific membrane antigen (PSMA) PET/CT was compared with the results and clinical factors of PSA, PSA kinetics, primary treatment, and Gleason score based on follow-up. Of the 52 patients included in the study, 42 (80.8%) were initially treated with RP and 10 (19.2%) were managed with RT.

At the time of the PSMA PET/CT scan, 21 (40.3%) patients were undergoing androgen deprivation therapy (ADT) and 26 (50%) had a PSA doubling time ≤10 months. At least one malignant area was found in 34 (65.4%) patients, and 18 (34.6%) patients had a negative PSMA PET/CT scan with no detectable disease.

Multivariate logistic regression showed that the patients’ Gleason scores were significantly associated with positive PSMA PET/CT scans. PSA values at the time of the PSMA PET/CT scans were also positively associated with imaging positivity, but no significant association was found between PSMA PET/CT status and time to relapse.

Use of ADT was not found to be related to PSMA PET positivity, and no association was found between PSMA PET positivity and primary therapy in the setting of BCR.

Overall, the study showed promising results for the use of 68Ga-PSMA. Positivity of the imaging was found to be associated with PSA at PET imaging time, PSA doubling time, Gleason score, and TNM staging. PET/CT is useful for early detection of disease recurrence in patients with PCa and BCR.