Introduction & Objectives
Traditional imaging modalities for advanced prostate cancer include PET/CT with choline-based tracers. Such modalities provide limited detection rates, particularly in patients with low-PSA levels during the early stages of biochemical recurrence. 68Ga PSMA-PET is an emerging imaging that provides the ability to selectively identify and localize metastatic prostate cancer. Current reports suggest improved detection rates in patients with low-levels of PSA in the setting of biochemical recurrence. We undertook a systematic review and meta-analysis of reported predictors of positive 68Ga PSMA-PET/CT in the setting of advanced prostate cancer.
Material & Methods
We performed critical reviews of MEDLINE, EMBASE, ScienceDirect, Cochrane Libraries and Web of Science databases in April 2016 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Quality assessment was performed using Quality Assessment if Diagnostic Accuracy Studies-2 tool. Meta-analysis and meta-regression of proportions were performed using a random-effects model with pre-PET PSA levels as the dependent variable.
Seventeen articles including 1,841 patients were analysed. Overall percentage of positive 68Ga PSMA-PET was 44% (95% CI: 18-72%) for primary staging patients and 76% (95% CI: 66-85%) or biochemical recurrence (BCR) patients. Positive 68Ga PSMA-PET scans for BCR patients increased with higher pre-PET PSA. For PSA categories 0-0.2ng/ml, 0.2-1ng/ml, 1-2 ng/ml and > 2 ng/ml, the percentage positive were 30%, 53%, 78% and 96% respectively. Shorter PSA doubling time increased 68Ga PSMA-PET positivity.
In the setting of biochemically recurrent prostate cancer, pre-PET PSA predicts the risk of positive 68Ga PSMA-PET. Compared to traditional imaging modalities, 68Ga PSMA-PET appears to provide improved prostate cancer detection at lower PSA levels.