Introduction

Patients with low-risk prostate cancer (PCa) at diagnosis are at risk for upgrading or upstaging on radical prostatectomy (RP). The possibility of occult aggressive disease is a concern for active surveillance (AS). Accordingly, AS is commonly restricted to men with 3 or fewer positive cores. The goal of this study was to model the relationship between the number of positive cores and the risk of adverse pathology in order to determine a threshold number of cores for AS._x000D_

Methods

We identified a cohort of 1,820 men who underwent RP at Memorial Sloan Kettering Cancer Center (MSKCC) between January 2000 and August 2016, and had low risk PCa. A comparable cohort of 1,469 French patients treated between December 2004 and November 2012 was identified. Adverse pathology was defined as Gleason score ≥ 4+3, seminal vesicle invasion or lymph node involvement. The association between number of biopsy cores and the risk of adverse pathology was analyzed using locally weighted scatterplot smoothing._x000D_

Results

In the MSKCC cohort, 171 (9.4%) patients had adverse pathology at RP, compared to 48 (3.3%) in the French cohort. There was a small increase in the risk of adverse pathology with the number of positive cores: patients with 1 positive core had a 4% risk which increased to 8% for patients with 12 positive cores. The increase in risk was smooth, with no discontinuities suggesting an obvious threshold for AS eligibility (Figure 1). There were some differences between cohorts, with the change in risk with increasing cores being flatter in MSKCC cohort. However, even in the French cohort, there were not large differences in risk by number of cores._x000D_

Conclusions

There is no number of positive cores threshold associated with a sharp increase in the risk of adverse pathology. Consequently, patients should not be excluded from AS solely based on the number of positive cores. _x000D_

Funding

None