Performance of PRIMARY Score based on PSMA-PET imaging in suspected prostate cancer patients with different PSA...

To refine the optimal PRIMARY score thresholds across different PSA ranges, enhancing diagnostic accuracy for clinically significant prostate cancer (csPCa).

The study retrospectively analyzed 373 patients who underwent PSMA PET/CT scans for suspected csPCa between June 2021 and December 2023. The diagnostic efficacy of PRIMARY score was independently assessed using 68Ga-PSMA PET/CT. Receiver-operating characteristic curve analysis was used to estimate the diagnostic performance. The diagnostic efficacy of the PRIMARY score with different thresholds in different PSA ranges was also calculated and compared.

The PRIMARY score maintains high diagnostic accuracy either in group of PSA ≤ 20 ng/mL or PSA > 20 ng/mL, with an AUC exceeding 0.8 at appropriate thresholds. Notably, in patients with PSA > 20 ng/mL, a PRIMARY score threshold of 4 demonstrated enhanced diagnostic accuracy compared to a threshold of 3, significantly improving specificity from 70.6% to 91.2% while maintaining high sensitivity (from 99.2% to 98.4%). Consequently, 91.2% (31/34) patients could avoid unnecessary biopsies, at the expense of missing 1.6% (2/125) of csPCa cases.

Across different PSA ranges, the PRIMARY score based on ⁶⁸Ga-PSMA PET/CT imaging is useful in the diagnosis of csPCa. A threshold of 3 for PSA ≤ 20 ng/mL and a threshold of 4 for 20 ng/mL < PSA ≤ 50 ng/mL respectively demonstrated favorable diagnostic performance.