Presentation Authors: Guan Hee Tan*, Antonio Finelli, Ardalan Ejaz Ahmad, Marian Wettstein, Alexandre Zlotta, Neil Fleshner, Robert Hamilton, Girish Kulkarni, Khaled Ajib, Gregory Nason, Nathan Perlis, Toronto, Canada
Introduction: To minimize morbidity of surgery or radiation, active surveillance (AS) is standard of care in low-risk prostate cancer (PC). Predicting which men on AS will progress and require active treatment is challenging. This study describes a novel total cancer location (TCLo) density index and aims to determine its performance in predicting clinical progression (CP) and grade progression (GP).
Methods: This was a retrospective study of patients on AS after confirmatory biopsy (CBx). We excluded patients with Gleason 7 or higher at CBx, less than 2 years follow-up and incomplete data. TCLo was the number of locations with positive cores at diagnosis (DBx) and CBx. TCLo density was TCLo / prostate volume (PV). CP was progression to any active treatment while GP occurred if Gleason 7 or higher was identified on repeat biopsy or surgical pathology. Independent predictors of time to CP or GP were estimated with Cox regression using age, PSA, number of positive CBx cores, TCLo and TCLo density as predictors. Kaplan-Meier analysis compared progression-free survival curves between high and low TCLo density groups. Test characteristics of TCLo were explored with receiver operating characteristic (ROC) curves.
Results: Between 2012-2015, 421 patients had a CBx. We included 181 patients who met inclusion criteria. The mean age of patients at the start of AS was 62.6 years (SD=7.13) and the median PSA at diagnosis was 5.16 ng/mL (IQR=3.44). Mean PV was 45.0 mL (SD=18.1). Median follow-up duration was 60.9 months (IQR=23.4). The median TCLo density was 0.049 (IQR=0.06). A high TCLo density score (>0.05) was independently associated with time to CP with HR 4.7 (95% CI: 2.62-8.42, p < 0.001) and GP with HR 4.25 (95% CI: 2.06-8.74, p < 0.001) (Figure 1). TCLo density performed better than percentage positive cores at confirmatory biopsy in predicting CP (Figure 2).
Conclusions: TCLo density has the potential to stratify patients into low or high risk for clinical and grade progression while on AS for low-risk PC. This should be validated with a larger prospective sample population.