Updating the prostate cancer risk indicator for contemporary biopsy schemes

Introduction and objective: The prostate cancer risk indicator is a validated tool for predicting the chance of a screen detected prostate cancer to be classified as indolent, partially based on lateralized sextant biopsies. Our objective is to extract correction factors for adjustment of the model, addressing contemporary extended biopsy schemes. Materials and methods: Post-mortem 18-core biopsy results of men who died of unrelated causes, but were diagnosed with prostate cancer post-mortem were used to provide details on prostate biopsies and whole mount specimens. For each of the 18-core biopsies showing cancer, Gleason score, number of positive cores, location in the gland and percentage of cancer involvement were determined and correlated to final pathology. Total length of cancer tissue in a 6-core scheme was related to the length in 12 and 18-core schemes to compute correction factors. Furthermore, upgrading on extended biopsies and final pathology was evaluated. Results: Data from 33 autopsied men were included. The 18 and 12-core biopsies showed 192.72 mm and 143.76 mm of prostate cancer, compared to 70.80 mm with lateralized sextant biopsy, resulting in correction factors of 2.72 and 2.03 for 18 and 12-core schemes respectively. Upgrading in Gleason score on extended biopsy regimens compared to lateralized sextant biopsy occurred in 33% (11/33) of the cases. Conclusion: Based on autopsy data, the present correction factors provide a support in the adjustment of the prostate cancer risk indicator towards more extended contemporary biopsy schemes, eventually leading to a more accurate prediction of the probability of indolent cancers and assisting patients and clinicians to make appropriate choices in daily practice.

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