About 40 percent of newly diagnosed prostate cancer patients are found to have a low-risk form of the disease. For them, close monitoring, or active surveillance, can help men with slow-growing tumors manage their prostate cancer while reducing harm from overdiagnosis and overtreatment.
But a new prospective study by researchers from the University of Toronto that enrolled men who had slightly higher risk scores has found that despite close monitoring, metastatic disease developed in 3 percent of patients seven years after diagnosis.
Intermediate-risk prostate cancer is characterized by a Gleason score of 7 with a prostate-specific antigen (PSA) level higher than 10/ng/mL. Low risk is a Gleason score of 6 or less with a PSA of 10/ng/mL or less.
The findings were published in The Journal of Urology in May 2016. Of the 980 men analyzed, 211 were classified as intermediate risk. Fifteen eventually died of prostate cancer, four died of other causes, and 11 had metastases at the close of the study. The risk of metastatic disease increased to 10 percent in patients with a Gleason score of 7.
The study's authors say active surveillance appears safe in patients at low risk and in some patients at intermediate risk.
But patients who have elements of Gleason pattern 4 after biopsy had a threefold to fourfold increased risk for eventual metastasis. They said those patients at intermediate risk (indicated by a Gleason score of 3 + 4 = 7 and/or a PSA of 10-20 ng/mL) should be offered surveillance with caution.