Israel Medical Association Journal

Background: Ga-prostate-specific membrane antigen positron emission tomography/computerized tomography (Ga-PSMA PET/CT) is part of the initial workup of patients with intermediate and high-risk prostate cancer provided by the Israeli national health services.

Objectives: To assess the incidence of metastatic spread in consecutive patients with newly diagnosed cancer, and the potential added value of Ga-PSMA PET/CT to the staging imaging algorithm.

Methods: Patients with newly diagnosed intermediate- and high-risk prostate cancer were referred for initial staging by Ga-PSMA PET/CT between May 2016 and April 2017. Blood prostate-specific antigen (PSA) levels, clinical history, imaging reports and histopathological reports (including Gleason scores) were obtained. Maximal standardized uptake values (SUVmax) were determined for the primary lesions detected within the prostate.

Results: The study included 137 consecutive patients with intermediate- and high-risk disease who underwent Ga-PSMA PET/CT staging. Of these, 75 had Ga-PSMA uptake in both prostate lobes, 57 had unilateral uptake, and 5 patients had no uptake. SUVmax in the primary tumor correlated significantly with PSA levels. Thirty-five patients had increased uptake compatible with metastatic disease involving lymph nodes, bone, and viscera. Twenty-seven patients had available bone scintigraphy results: 18 (69%) of their 26 bone metastases detected by Ga-PSMA PET/CT were missed on bone scintigraphy.

Conclusions: Ga-PSMA PET/CT shows promise as a sole whole-body imaging modality for assessing the presence of soft tissue and bone metastases in the setting of prostate cancer.

Background: Radiotherapy to the prostate bed is used to eradicate residual microscopic disease following radical prostatectomy for prostate cancer. Recommendations are based on historical series. 

Objectives: To determine outcomes and toxicity of contemporary salvage radiation therapy (SRT) to the prostate bed. 

Methods: We reviewed a prospective ethics committee-approved database of 229 patients referred for SRT. Median pre-radiation prostate-specific antigen (PSA) was 0.5 ng/ml and median follow-up was 50.4 months (range 13.7–128). Treatment was planned and delivered using modern three-dimensional radiation techniques. Mean bioequivalent dose was 71 Gy (range 64–83 Gy). Progression was defined as two consecutive increases in PSA level > 0.2 ng/ml, metastases on follow-up imaging, commencement of anti-androgen treatment for any reason, or death from prostate cancer. Kaplan-Meier survival estimates and multivariate analysis was performed using STATA. 

Results: Five year progression-free survival was 68% (95%CI 59.8–74.8%), and stratified by PSA was 87%, 70% and 47% for PSA < 0.3, 0.3–0.7, and > 0.7 ng/ml (P < 0.001). Metastasis-free survival was 92.5%, prostate cancer-specific survival 96.4%, and overall survival 94.9%. Low pre-radiation PSA value was the most important predictor of progression-free survival (HR 2.76, P < 0.001). Daily image guidance was associated with reduced risk of gastrointestinal and genitourinary toxicity (P < 0.005). 

Conclusions: Contemporary SRT is associated with favorable outcomes. Early initiation of SRT at PSA < 0.3 ng/ml improves progression-free survival. Daily image guidance with online correction is associated with a decreased incidence of late toxicity.