Are patients with Gleason 6 pathology safe from developing metastatic castration-resistant prostate cancer (mCRPC)?

Abstract

110 Background: Prostate cancer may remain clinical unapparent for decades, however at the stage of metastatic castration resistant prostate cancer (mCRPC), patients have only limited survival even with new therapeutic options. Recent evidence from histology studies regarding random prostate biopsies hint toward a relationship between higher biopsy Gleason score and the development of mCRPC. A few patients with initial low risk prostate cancer also seem to develop mCRPC. However, prostate biopsy underestimates final pathology in about one third of patients. We therefore evaluated the final whole gland pathology from radical prostatectomy to better assess the risk of progressing to mCRPC for patients with Gleason 6 prostate cancer in particular. Methods: Clinical data was assessed for patients with confirmed mCRPC between 3/2007 and 10/2014. Whole gland pathology workup was not available for patients with either metastatic disease on diagnosis, external radiation therapy or no curatively intended initial therapy. Results: Out of 605 screened patients we identified a total of 77 patients with confirmed mCRPC. Mean PSA at initial diagnosis was 29.5 ng/mL (range 1 - 58 ng/mL ). Mean PSA at the end of follow up was 34.1 ng/mL (range 1 - 71 ng/mL ). A total of 30 patients died during follow up. Distribution of Gleason scores for gleason 6, 7, 8, 9 and 10 were 2, 24, 28, 18, 5 patients respectively. Pathological evaluation obtained from laparoscopic or retropubic radical prostatectomy was available in 43 of 77 cases. cases. Interestingly, out of the only two patients with a documented gleason score of 6, one had radiation/I125 brachytherapy while the other had primary anti hormonal therapy. Therefore an understaging may be possible. Out of the confirmed final pathologies, non of the patients had a Gleason score below 7. Conclusions: Our observations suggest a non significant occurrence of mCRPC during the development of prostate cancer for patients with Gleason pathology of less than 7. Our results may potentially help better counseling for patients and need further validation in a larger series.