MP14-18 VERY LOW RISK VS. LOW RISK PROSTATE CANCER DESIGNATIONS IN AN ACTIVE SURVEILLANCE COHORT

Abstract

INTRODUCTION AND OBJECTIVES: NCCN guidelines differentiate between very low risk (VLR) and low risk (LR) prostate cancer based onEpsteinCriteria. Thesecategories havenot beenwell studied in anactive surveillance population. We sought to determine if these risk groups were meaningful in regards to recategorization of overall risk category on confirmation and surveillance biopsies in an active surveillance population. METHODS: Men eligible for active surveillance were designated eitherVLR (stageT1c,PSAdensity 0.15ng/mL/mL,Gleasonscore 6, 2 positive biopsy cores, 50% cancer per core) or LR (stage T1c/T2a, PSA 10 ng/mL, and Gleason score 6). Risk recategorization was defined as Gleason 7, T2b or greater, and PSA > 10 ng/mL on subsequent biopsy or clinical treatment of prostate cancer. Basic demographics including age, race, BMI, PSA and prostate volume were collected. Comparisons between VLR and LRwere conducted using chisquare test, t-test, and Mann-Whitney U test. Logistic regression was used to examine the association between initial risk category and recategorization at confirmation and surveillance biopsies. RESULTS: 122 men were initially categorized as VLR while 62 were LR. Average age of the cohort was 65.4 7.0 years with 85.4% Caucasian. There was no difference in age, BMI or race between risk categories. Median prostate volume was 44.5 (IQR 34.0 61.5) mL vs. 31.0 (IQR 24.8 39.5) mL (p<0.001) in the VLR and LR groups, respectively. Overall, men were followed for a median of 36.6 months ( IQR 29.9-52.5). There were no statistically significant differences in the frequency of risk recategorization among VLR patients with 1 vs. 2 cores positive on initial biopsy. At confirmation biopsy, 15 (12.3%) of VRL and 18 (29.0%) of LR were recategorized (p1⁄40.005). After adjustment for age, PSA, PCA3, and the presence of perineural invasion, LR patients were significantly more likely to be recategorized at confirmation biopsy compared to VLR (OR 1⁄4 3.47, 95 % CI 1⁄4 [1.23 9.83] p1⁄40.019). During follow up surveillance biopsies, 21(17.2%) of VRL and 18 (29.0%) of LR were recategorized. (p1⁄40.064). CONCLUSIONS: Patients initially designated LR have a higher risk for recategorization during both confirmation and surveillance biopsies compared to those with VLR disease. However, it should be noted that approximately 25% of all men initially believed to have VLR will ultimately be found to have more aggressive pathology. This calls into question whether this VLR designation provides a false sense of security for patients and treating physicians.