Retrospective correlation of 68ga-psma uptake with clinical parameters in prostate cancer patients undergoing definitive radiotherapy.

Abstract

The aim of the study is to investigate the correlation between the intensity of prostate-specific membrane antigen (PSMA) uptake in primary tumor and clinico-pathological characteristics of non-metastatic prostate cancer patients treated with definitive radiotherapy (RT). Using the clinical data of 201 prostate cancer patients who were referred for 68Ga-PSMA-positron emission tomography (PET/CT) for staging and RT planning, we analyzed the correlations among intermediate- or high-risk disease based on Gleason score (GS), prostate-specific antigen (PSA) level, D'Amico risk group classification, and maximum standardized uptake (SUVmax) of primary tumor. Primary tumor was visualized via 68Ga-PSMA-PET/CT scan in 192 patients (95.5%). The median SUVmax of primary tumor and metastatic lymph node were 13.2 (range 3.3-83.7) and 11.4 (range 3.6-64.5), respectively. A significant moderate correlation was observed between PSA level and median tumor SUVmax as measured by 68Ga-PSMA-PET/CT (Spearman = 0.425; p < 0.001). Patients with serum PSA > 10ng/mL, GS > 7, D'Amico high-risk group classification, and pelvic lymph node metastasis had significantly higher tracer uptake in primary tumor than their counterparts. The median SUVmax of primary tumor was highest in patients with GS 9. The primary tumor detection rates of 68Ga-PSMA-PET/CT were 83%, 92%, and 99% for patients with serum PSA ≤ 5.0ng/mL (14 patients, 7%), PSA 5.1-10.0ng/mL (45 patients, 22%), and PSA > 10ng/mL (142 patients, 71%), respectively. We demonstrated a correlation between prostate tumor characteristics and PSMA tracer uptake. Patients with serum PSA > 10ng/mL, GS > 7, D'Amico high-risk group classification, and pelvic lymph node metastasis had significantly higher SUV than their counterparts. In addition, the primary tumor detection rate was higher in patients with serum PSA > 10ng/mL and GS > 7.