Abstract: PD55-07
Sources of Funding: PCORI ME-1408-20318

Introduction

Active Surveillance (AS) of localized prostate cancer (PCA) has been shown to be a safe alternative to immediate curative treatment for men with favorable risk diagnoses; very low risk (VLR) and low risk (LR). The relevance of stratifying patients into VLR and LR categories for the purposes of enrollment and analysis is in question. Our objective was to compare the difference in cancer risk for men with VLR and LR disease.

Methods

We used the clinical data from 1,032 VLR and 446 LR patients enrolled in the Johns Hopkins prospective AS program to predict the pathologic Gleason score (PGS) as the outcome of interest. Predictions were obtained by extending a statistical model developed in the VLR cohort (SITE PUBLICATION HERE), to estimate different probability distributions of PGS between VLR and LR groups. This approach leverages 1) repeated PSA and biopsy measurements taken in the course of AS, 2) post-prostatectomy PGS findings in AS patients to identify patterns of clinical measurements associated with more aggressive pathology. The model is agnostic with regard to differential risk a priori (i.e., biopsy extent of cancer).

Results

LR patients were significantly more likely than VLR patients to have a PGS above 6 (p<0.01). The estimated probability of PGS=6 for VLR and LR patients was 71% and 57%, respectively (Table). Both VLR and LR patients were unlikely to have predicted PGS of >4+3; 9.2% and 10%, respectively._x000D_ _x000D_

Conclusions

As compared to VLR, men with LR PCA were more likely to harbor pathologically significant disease, suggesting that this distinction is clinically relevant. Long term cancer specific outcomes will be necessary to confirm the clinical significance of these findings.

Funding

PCORI ME-1408-20318