RNA expression-based molecular testing has the potential to improve clinical decision making as an adjunct to histopathologic interpretation of prostate cancer biopsies. The Oncotype Dx Prostate Cancer Assay has been proposed as a predictor of more severe pathology at prostatectomy, but its true clinical value is uncertain. We hypothesized that some of this assay's predictive utility relates to its correlation with histopathologic features apparent, but not typically reported, on prostate biopsies. In a retrospective, single-center cohort, an RNA-based Genomic Prostate Score (GPS) was determined on prostate biopsies. We retrospectively reviewed the histopathologic features of the biopsy cores that had received a GPS and assessed tumor length, amount and type of Gleason pattern 4, and type of stromal reaction. Associations between GPS and histopathologic features were assessed by linear mixed models. From 296 patients, 319 biopsies received a GPS from May 2013 to August 2015. Among the types of Gleason pattern 4, expansile cribriform, simple cribriform, poorly formed, and fused patterns were associated with higher GPS, with expansile cribriform having the strongest association. The glomerulation pattern was associated with lower GPS. Increasing stromal reaction was also positively correlated with GPS. A model incorporating these pathological features accounted for 36.9% of the variation in GPS. Stromal reaction and type of Gleason pattern 4 are histopathologic features that are not typically reported on prostate biopsy that correlate with GPS. These data suggest that more detailed analysis of prostate histopathology might substitute for some of the information gained from this molecular diagnostic.
The Journal of urology. 2019 Feb 15 [Epub ahead of print]
Nancy Y Greenland, Li Zhang, Janet E Cowan, Peter R Carroll, Bradley A Stohr, Jeffry P Simko
Department of Anatomic Pathology, University of California , San Francisco , California ., Department of Medicine, University of California , San Francisco , California ., Department of Urology, University of California , San Francisco , California .