Adding Biopsy Factors to PRIAS Criteria May Help Predict Unfavorable Prostate Cancer

By Will Boggs MD

July 07, 2015

NEW YORK (Reuters Health) - Adding biopsy factors to existing Prostate Cancer Research International: Active Surveillance (PRIAS) criteria may boost the ability to detect prostate cancer that is unfavorable for active surveillance, researchers from Italy report.

"The risk of misclassification of patients on active surveillance based on PRIAS criteria is 26%," Dr. Giorgio Ivan Russo from the University of Catania told Reuters Health by email. "We proposed to incorporate some biopsy features in order to reduce that risk."

The PRIAS criteria include clinical stage T1c or T2 disease, PSA <=10 ng/mL, Gleason score <=6, PSA density <0.2 ng/mL, and one or two positive biopsy cores.

Dr. Russo's team assessed performance capabilities of biopsy factors when added to the PRIAS criteria in 143 men who underwent radical prostatectomy but were eligible for active surveillance.

Two-thirds of these men had favorable disease and one-third had unfavorable disease, the researchers report in Prostate Cancer and Prostatic Disease, online June 2.

On multivariate analysis, the inclusion of maximum cancer length (MCL), cumulative cancer length (CCL), cumulative length of positive cores (CLPC) and cancer involvement of positive cores (CIPC) significantly increased the accuracy of the model in predicting unfavorable disease.

These models were especially beneficial when the probability of finding unfavorable disease ranged between 15% and 50%. At a CIPC cutoff of 28.5, they would miss no more than 16.83% of men with unfavorable disease.

"Our findings suggest that models including biopsy factors could not only predict unfavorable disease in men eligible for active surveillance but could also minimize the risk of missing high-grade and non-organ-confined cancers," the researchers say.

"The model cannot replace the entire PRIAS model," Dr. Russo said. "However, urologists involved in PRIAS protocol can take into account that biopsy features significantly improve accuracy of the PRIAS model itself."

Dr. Marc Dall'Era from the University of California, Davis, in Sacramento told Reuters Health by email, "Although adding these findings will help identify patients with extremely low-risk prostate cancer, I am concerned that if we were to include such stringent criteria, we will further limit the number of men eligible for active surveillance. Since there is no evidence that the primary outcome measure of this study (adverse pathology) which included any higher-stage disease or any Gleason 7 (3+4 or 4+3) correlates with longer-term outcomes such as disease progression over time or prostate cancer specific mortality, these criteria should not be generalized across the board."

"Prostate cancer overtreatment remains a substantial problem for some men with this disease," said Dr. Dall'Era, who studies active surveillance and clinical outcomes for men with prostate cancer. "As we improve our abilities to identify men who can be carefully managed with active surveillance, as well as improve our methods for keeping track of localized tumors, this problem as well as much of the controversy surrounding PSA screening will diminish."

Dr. Jeri Kim from The University of Texas MD Anderson Cancer Center in Houston said, "The big point should be that despite the limitations of selection tools used, many men do well on active surveillance."

"So far none of the prediction models for low-volume/low-grade prostate cancer have been prospectively validated," Dr. Kim told Reuters Health by email. "Also, none of the models takes into consideration tumor biology or life expectancy. I think eventual incorporation of imaging, biomarkers (for aggressive disease), and host factors (comorbidities, life expectancy) as selection tools for active surveillance will reduce the odds of missing clinically significant disease and prevent men from undergoing unnecessary intervention."

SOURCE: http://bit.ly/1JCiPlS

Prostate Cancer Prostatic Dis 2015.

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