A genomic prostate score (GPS) has little value in predicting adverse outcomes in men who have undergone a period of active surveillance before having a radical prostatectomy, according to a study published in the Journal of Clinical of Oncology.
The hazard ratio for adverse pathology using the 17-gene Oncotype DX Genomic Prostate Score did not reach statistical significance in a multivariate model (HR, 1.17; P = .066). This model took into account factors such as the prostate-specific antigen density (PSAD) and the Gleason grade group at diagnosis.
“In our study, the independent association of GPS with adverse pathology after initial active surveillance was not statistically significant,” Daniel W. Lin, MD, of the Fred Hutchinson Cancer Research Center in Seattle, and colleagues wrote.
There was also no association between the GPS and having upgraded biopsy findings during active surveillance.
Active surveillance is the “preferred management strategy” for men with low-risk prostate cancer, observed Dr. Lin and colleagues, but its use is often tempered by the worry that there may be underlying pathology that is not detected using routine clinical measures such as prostate-specific antigen testing. In their study, the investigators looked to see if using the GPS could help risk-stratify men undergoing active surveillance.
They noted that the biopsy-based genomic test had been shown to predict adverse surgical pathology and recurrence in men with low- and intermediate-risk prostate cancer who had undergone immediate radical prostatectomy. The team therefore wanted to clarify the test’s role in men who had been initially managed with a period of active surveillance.
To calculate the GPS, the investigators retrospectively analyzed diagnostic biopsy samples that had been prospectively collected from 432 men in the Canary Prostate Active Surveillance Study. The primary endpoint was adverse pathology in men who underwent radical prostatectomy after initial surveillance. Adverse pathology was defined as a Gleason grade of 3 or greater, a staging of pT3a or higher (with or without N1), or both.
After a median follow-up of 4.6 years, 167 (39%) men experienced upgrading of their prostate cancer at a surveillance biopsy, with 51 (12%) being upgraded to a Gleason grade group of 3 or higher. A total of 101 (23%) men had radical prostatectomy at a median of 2.1 years after their diagnostic biopsy, and just over half (n = 52; 51%) had adverse pathology at this time point.
GPS was associated with adverse pathology when the diagnostic Gleason grade group was taken into account (HR, 1.18; P = .030) but not when the investigators adjusted for both PSAD and diagnostic Gleason grade group. By contrast, PSAD (HR, 1.75; P = .025) was significantly associated with adverse pathology.
“Adding GPS to a model containing PSAD and diagnostic [Gleason grade group] did not significantly improve stratification of risk for [adverse pathology] over the clinical variables alone,” Dr. Lin and colleagues concluded.
This work was supported by the Canary Foundation, the Department of Defense, the National Institutes of Health, and Genomic Health. The authors disclosed relationships with Genomic Health and other companies.
SOURCE: Lin DW et al. J Clin Oncol. 2020 Mar 4. doi: 10.1200/JCO.19.02267.