Occult High-risk Disease in Clinically Low-risk Prostate Cancer with ≥50% Positive Biopsy Cores: Should National Guidelines Stop Calling Them Low Risk?

Objective: To identify contemporary, clinically low-risk patients with ≥50% cores positive and compare the risk of upgrading at prostatectomy with other low- or intermediate-risk patients.

Materials And Methods: We studied 14,902 patients with prostate cancer in the Surveillance, Epidemiology, and End Results database in 2010-2011 treated with prostatectomy. Patients were categorized by National Comprehensive Cancer Network clinical risk groups, separating low-risk patients by percent positive biopsy cores (PBC). We measured incidence of pathologic high-risk disease, defined as pT3a-T4 or Gleason 8-10, and multivariable logistic regression was used to determine if patients with clinical low-risk disease and ≥50% PBC were similar to other low- or intermediate-risk patients. This analysis was repeated with favorable and unfavorable intermediate risk.

Results: At prostatectomy, 9.2% of clinically low-risk patients with <50% PBC, 18.6% of clinically low-risk patients with ≥50% PBC, and 27.6% of clinically intermediate-risk patients had occult, high-risk disease (P <.001). On multivariable logistic regression, low-risk patients with ≥50% PBC were more likely than low-risk patients with <50% PBC to have pathologic high-risk disease (adjusted odds ratio [AOR] 2.28, 95% confidence interval 1.90-2.73, P <.001), had similar risk to favorable intermediate patients overall (AOR 1.09, 0.91-1.31, P = .33), and had higher risk than favorable intermediate patients aged over 60 years (AOR 1.28, 1.00-1.64, P = .04). Low-risk patients with ≥50% PBC had a mean tumor size similar to unfavorable intermediate-risk patients (21.3 vs 21.0 mm, P = .82).

Conclusion: Nearly 1 in 5 clinically low-risk prostate cancer patients with ≥50% PBC harbor occult pT3a-T4 or Gleason 8-10, suggesting that national guidelines should not classify low-risk patients with ≥50% cores positive as "low risk," and patients should be made aware of this excess risk if considering active surveillance.