NEW YORK - After a decade of follow-up in the Prostate Cancer Research International Active Surveillance (PRIAS) study, researchers have confirmed that active surveillance is a safe treatment option for men with low-risk prostate cancer.
"However," they say, "some changes could be made to the follow-up protocol to safely increase the number of men who remain on active surveillance."
Dr. Leonard P. Bokhorst of Erasmus University Medical Center in Rotterdam, the Netherlands, and colleagues analyzed data on more than 5,000 men in 18 countries followed in PRIAS, including 622 who were followed more than five years and 107 were followed more than 7.5 years.
The median age at diagnosis was 65.9 years.
Original inclusion criteria included Gleason score 3+3 or lower, stage cT2c or lower, and prostate-specific antigen (PSA) 10 ng/ml or lower. PSA tests were scheduled every three months and digital rectal examinations were scheduled every six months during the first two years of study, then less often later. Criteria to recommend starting active treatment include Gleason score higher than 3+3, more than two positive cores, and stage higher than cT2.
Median PSA for the study population was 5.7 ng/ml. Most men (69%) had one positive biopsy core, with Gleason score of 3+3 (99%) and a clinical stage of T1c (88%).
Almost 3,400 men received at least one repeat biopsy during follow-up and some received up to five biopsies.
Overall, 1,768 men discontinued active surveillance during follow-up, 1,102 due to protocol-based reclassification. Other reasons for discontinuations included anxiety, switch to watchful waiting, death, and loss to follow-up. Two-thirds (67%) of the men were treated with either radical prostatectomy or radiation therapy after discontinuation. Only 3% received hormonal therapy.
Almost half (48%) of the patients were still on active surveillance after five years and 27% were on active surveillance at 10 years, the researchers reported online June 19 in European Urology.
The team had pathology data on 360 men who had radical prostatectomy. Of the men who switched to treatment because of protocol-based reclassification, 82 (30%) had favorable pathological outcomes, 85 (34%) had intermediate outcomes, and 100 (36%) had unfavorable outcomes.
Mortality from prostate cancer was less than 1% during follow-up.
Because of the higher rate of unfavorable treatment outcomes, the researchers recommended a change in the PRIAS protocol.
"Instead of an immediate switch to active treatment if more than two cores are positive, men should receive further investigation to confirm higher risk disease," the researchers write. They recommend examination by magnetic resonance imaging because its negative predictive value for Gleason upgrading is near 100%.
They concluded, "Criteria used to recommend a switch to active treatment do not seem selective enough to avoid unnecessary switches to active treatment."
Dr. Bokhorst did not respond to a request for comment.
The Prostate Cancer Research Foundation, Rotterdam, supports the PRIAS study. The authors made no disclosures.
Eur Urol 2016.