PSMA-PET shows value as a prognostic biomarker for recurrence in prostate cancer

The addition of prostate-specific membrane antigen (PSMA)-PET to presurgical Cancer of the Prostate Risk Assessment (CAPRA) score was shown to significantly improve the risk assessment for biochemical recurrence-free survival (BCR-FS) in patients with prostate cancer compared with CAPRA score alone, according to findings published in European Urology.¹

In total, 91 (38%) patients experienced BCR, and 41 (17%) patients experienced PSMA-PET N1/M1.

“In patients with prostate cancer considered for surgery, PSMA-PET can provide information on the risk of recurrence after surgery, before the surgery even happens. The imaging tool improves personalized treatments by helping the urologist decide whether or not to perform surgery, and to guide the surgical plan and the follow-up management after surgery,” said lead author Loïc Djaïleb, MD, PhD, in a news release on the findings.² Djaïleb is a visiting associate professor at the David Geffen School of Medicine at the University of California, Los Angeles.

The data were from a post hoc follow-up study of a prospective phase 3 trial (NCT03368547, NCT02611882, NCT02919111) that enrolled 277 patients who underwent radical prostatectomy and pelvic lymph node dissection from December 2015 to December 2019. In total, 37 patients were lost to follow-up, resulting in clinical follow-up data from 240 (87%) patients. Median follow-up time among all participants was 32.4 months after surgery.

Patients’ 68Ga-PSMA-11-PET scans were each read by 3 blinded independent readers. PSMA prostate uptake and PSMA-PET extraprostatic disease (N1/M1) were then compared with CAPRA and CAPRA-Surgery (CAPRA-S) scores to assess the risk of BCR. CAPRA scores utilized PSA, MRI, and biopsy information, and CAPRA-S included a post-surgical analysis of the resected prostate and pelvic lymph nodes. BCR was defined as a PSA level increase of .2 ng/mL or higher after surgery or the initiation of a second prostate cancer-specific treatment more than 6 months following surgery.

In total, 91 (38%) patients experienced BCR, and 41 (17%) patients experienced PSMA-PET N1/M1. All 4 biomarkers of PSMA-PET prostate uptake, PSMA-PET N1/M1, CAPRA scores, and CAPRA-S scores were found to be significant predictors of BCR upon univariate analysis.

Further, adding PSMA-PET N1/M1 status to CAPRA scores was found to significantly improve the risk assessment for BCR compared with the assessment from CAPRA scores alone (c-statistic 0.70 [0.64–0.75] vs 0.63 [0.57–0.69]; P < .001). The risk assessment from the combination of CAPRA score and PSMA-PET N1/M1 status was found to be similar to that obtained using CAPRA-S score alone (P = .19).

Thus, PSMA-PET’s “implementation into the presurgical risk assessment with the CAPRA score improves the performance and reduces the difference with the reference standard (postsurgical CAPRA-S score),” according to the authors.

The investigators indicate that further research is needed to confirm the findings and evaluate the prognostic value of the imaging agent on other clinical outcomes.

“PSMA-PET is now the best imaging tool for prostate cancer. As it is still new, we need to learn how to use the information derived from PSMA-PET for the best outcomes of patients,” concluded co-senior author Thomas A. Hope, MD, in the news release.² Hope is a professor of radiology at the University of California, San Francisco.

References

1. Djaïleb L, Armstrong WR, Thompson D, et al. Presurgical 68Ga-PSMA-11 positron emission tomography for biochemical recurrence risk assessment: A follow-up analysis of a multicenter prospective phase 3 imaging trial. Eur Urol. Published online July 21, 2023. Accessed August 9, 2023. doi:10.1016/j.eururo.2023.06.022

2. PSMA PET imaging improves accuracy of predicting prostate cancer recurrence. News release. University of California, Los Angeles (UCLA), Health Sciences. July 25, 2023. Accessed August 9, 2023. https://www.newswise.com/articles/psma-pet-imaging-improves-accuracy-of-predicting-prostate-cancer-recurrence