A Novel Risk Score to Identify Insignificant Prostate Cancer in Unscreened Patients

Chicago—Management of patients with insignificant prostate cancer is increasingly utilizing active surveillance, and risk scores that use pre-operative factors have been developed. Lorenzo Dutto, MD, and colleagues recently evaluated the accuracy of nine separate tools developed to identify patients harboring insignificant prostate cancer. The assessment was conducted in a cohort of 2613 patients who underwent radical prostatectomy for Gleason score 3+3 prostate cancer.

The researchers developed and validated a novel risk score to correctly identify insignificant prostate cancer to be used in unscreened patient cohorts using non-dichotomized clinical predictors. They reported on their research during  a poster session at the 2017 ASCO Annual Meeting in a poster titled Development and External Validation of a Novel Risk Score to Identify Insignificant Prostate Cancer.

The cohort included 2799 patients who would have been candidates for active surveillance (Gleason score 6 only) and underwent robotic radical prostatectomy between 2006 and 2016 at a tertiary referral center. Analyses of the volume and grade of tumor in the resected prostate were conducted. Insignificant prostate cancer was defined as Gleason 3+3 only, index tumor volume <1.3 cm3, and total tumor volume <2.5 cm3 (updated European Randomized Study of Screening for Prostate Cancer definition).

The final analysis included 2613 patients. The researchers computed the accuracy (specificity, sensitivity, and area under the curve [AUC] of the receiver operator characteristic) of nine predictive tools. Using multivariate logistic regression with elastic net regularization, the researchers developed a novel tool to predict insignificant prostate cancer. The tool was developed using age at diagnosis, baseline prostate-specific antigen, transrectal ultrasonography volume, clinical T-stage, number of positive cores, and percentage of positive cores as predictors. The tool was validated in an external cohort of 441 unscreened patients undergoing surgery for Gleason score 6 prostate cancer.

All of the nine predefined tools rated poorly as predictors of insignificant disease; none of them reached the required AUC threshold of 0.7. The new tool performed well in training and in the validation cohorts.

In summary, the researchers said, “Pre-existing predictive tools to identify indolent prostate cancer have a poor predictive value when applied to an unscreened cohort of patients. Our novel tool shows good predictive power for insignificant prostate cancer in this population in training and validation cohorts. The inherent selection bias due to analysis of a surgical cohort is acknowledged.”

Source: Dutto L, Witt JH, Urbanova K, et al. Development and external validation of a novel risk score to identify insignificant prostate cancer. Abstract of a poster presented at the 2017 American Society of Clinical Oncology Annual Meeting, June 5, 2017, Chicago, Illinois.