Combining PI-RADS and PRIMARY scores improves prostate cancer detection

Combining the MRI Prostate Imaging Reporting and Data System (PI-RADS) score and the prostate-specific membrane antigen (PSMA)-PET/CT PRIMARY score into a composite P Score improves the accuracy of detecting clinically significant prostate cancer (csPCa), according to data published in the Journal of Urology.¹

The primary outcome measure for the study was the detection of clinically significant prostate cancer, defined as ISUP grade 2 or higher.

“The P score, integrating information from both MRI PI-RADS and PSMA PRIMARY score, gives the clinician a highly accurate picture of the presence or absence of clinically significant malignancy prior to prostate biopsy,” said lead author Louise Emmett, MBChB, FRACP, MD, in correspondence with Urology Times®. “In the long-term, this will enable us to safely avoid the need for biopsy in a high proportion of patients. It will also allow us to change the type of biopsy required for those patients in whom the chance of clinically significant malignancy is 100%, or even skip the biopsy and go straight to prostatectomy.Combining PRIMARY and PI-RADS scores could be a game-changer in how prostate cancer is diagnosed.”

Overall, findings showed that in a validation dataset, csPCa was identified in 0% of men with a P score of 1, 20% of men with a P score of 2, 52% of men with a P score of 3, 96% of men with a P score of 4, and 100% of men with a P score of 5. The area under the curve for the P score was 0.93 (95% CI, 0.90-0.96), compared with 0.89 for PI-RADS score alone (95% CI, 0.85-0.93; P = .039) and 0.84 for PRIMARY score alone (95% CI, 0.79-0.89; P < .001).

When scores 1-2 were characterized as negative and scores 3-5 were characterized as positive, the sensitivity for the P score was 94% (95% CI: 89-97), vs 89% with PI-RADS alone (95% CI: 83-93) and 86% with the PRIMARY score alone (95% CI: 79-91). The negative predictive value (NPV) for the P score in detecting International Society of Urological Pathology (ISUP) grade 2 cancer was 85%.

When defining csPCa as ISUP grade 3 or higher, the sensitivity of the P score was 99% (95% CI: 95-100), compared with 94% for PI-RADS alone (95% CI: 88-98) and 92% for PRIMARY score alone (95% CI: 85-97). The NPV for the P score in detecting ISUP grade 3 cancer was 98%.

In cases where the maximum standardized uptake value (SUV) was greater than 12 (correlating to a P score of 5), all patients were classified as having prostate cancer of ISUP grade 2 or higher, and 93% of patients were classified as having prostate cancer of ISUP grade 3 or higher.

For the study, the investigators developed the 5-point composite P score in a prospective dataset of 291 men with suspected prostate cancer. In total, 56% of these patients had csPCa. The validation sample included 227 men, of whom 67% had csPCa. Patients in both datasets had suspected prostate cancer, no prior biopsy, a recent MRI and ⁶⁸Ga-PSMA-11-PET/CT, and underwent subsequent transperineal biopsy to identify csPCa.

The primary outcome measure for the study was the detection of clinically significant prostate cancer, defined as ISUP grade 2 or higher. The secondary outcome measure was the detection of ISUP grade 3 or higher prostate cancer.

Based on these findings, the authors concluded, “The P score is easily calculated and improves accuracy for csPCa over both PI-RADS and PRIMARY scores. It should be considered when PSMA-PET is undertaken for diagnosis.”¹

Reference

1. Emmett L, Papa N, Hope TA, et al. Beyond prostate imaging reporting and data system: combining magnetic resonance imaging prostate imaging reporting and data system and prostate-specific membrane antigen–positron emission tomography/computed tomography PRIMARY score in a composite (P) score for more accurate diagnosis of clinically significant prostate cancer. J Urol. 2024;212(2):299-309. doi:10.1097/JU.0000000000004010