Association of extended core sampling with delayed intervention and pathologic outcomes for active surveillance patients: A population-based analysis.

INTRODUCTION:Combined systematic plus targeted biopsy sampling improves detection of clinically significant prostate cancer (PCa). Our objective was to evaluate whether extended core sampling at initial biopsy in active surveillance (AS) patients is associated with subsequent AS discontinuation and pathologic outcomes. METHODS:National Comprehensive Cancer Network (NCCN) low- and favorableintermediate-risk (FIR) AS patients diagnosed between 2010 and 2015 were identified from the Surveillance, Epidemiology, and End Results (SEER) Prostate with Watchful Waiting database. Prostate biopsy sampling was operationalized as: standard (10-12 cores), extended (13-20 cores), or super-extended (21+ cores). Sensitivity analyses using differing cutoffs was performed. Outcomes included delayed definitive intervention (radical prostatectomy [RP]/radiotherapy) and pathologic upgrading and/or downgrading in delayed RP patients. Multivariable logistic regression modelling adjusted for sociodemographic/oncologic variables was performed. RESULTS:This cohort included 42 459 patients (low-risk: 28 411; FIR:14 048); 25-29% and 3- 5% of patients underwent extended and super-extended core sampling, respectively, at diagnosis. Extended core sampling was associated with decreased odds of definitive intervention in low (odds ratio [OR] 0.89, p=0.003) and grade group 2 (GG2) FIR (OR 0.83, p=0.002) patients. Super-extended sampling was associated with decreased odds of definitive intervention in PSA 10-20 FIR patients (OR 0.65, p=0.02). Super-extended sampling was associated with decreased odds of upgrading to ≥GG2 disease in low-risk (OR 0.45, p=0.032) and to ≥GG3 disease in GG2 FIR patients (OR 0.67, p=0.044). CONCLUSIONS:This population-based analysis demonstrates that extended/super-extended sampling at diagnosis is associated with significantly decreased odds of AS discontinuation and pathologic upgrading in low/FIR AS patients. This highlights the significance of extended tissue sampling at initial biopsy to appropriately risk-stratify AS patients and minimize AS discontinuation rates.