The study reported that, “among men with localized prostate cancer detected during the early era of PSA testing, radical prostatectomy did not significantly reduce all-cause or prostate-cancer mortality, as compared with observation, through at least 12 years of follow-up. Absolute differences were less than 3 percentage points.”

Two subgroups of participants, those with PSA levels greater than 10 ng/mL and those with more aggressive tumors, demonstrated some longevity benefit from surgery.

“For most men with low-risk prostate cancer, there is no evidence they need immediate treatment,” said study co-author Gerald Andriole, MD, of the Washington University School of Medicine in St. Louis. “But the data suggest that men with high PSA levels and those with more aggressive tumors likely benefit from early surgery, and these men should undergo treatment, because their tumors are more likely to be lethal, if left alone.”

The study group included 731 men, averaging 67 years old, with tumors limited to the prostate. Participants were randomly assigned to surgery or observation.

During the follow-up period — a median of 10 years with some patients tracked for as long as 12 years — 71 of 364 men (47%) assigned to radical prostatectomy died, compared with 183 of 367 (49.9%) assigned to observation.

Of those who received surgery, 5.8% died from prostate cancer or treatment, compared with 8.4% assigned to observation. Adverse events within 30 days after surgery occurred in 21.4% of men, including one death.

The study’s conclusions were not universally accepted, however.

“Though, on the surface, these new data from PIVOT may imply that radical prostatectomy did not significantly reduce mortality in men with localized prostate cancer, when compared with observation, the data do show a demonstrated positive effect in prostate cancer-specific mortality [as well as a trend in overall mortality] in high-risk patients,” said David F. Penson, MD, MPH of Vanderbilt University in Nashville, TN, the health policy chair at the American Urological Association (AUA).

“This trend is evident, despite the fact that PIVOT is an undersized study [its enrollment of 731 men is not large enough to give an adequate confidence interval] and suffers from other flaws that impact its ability to fully assess the effects of treatment. Had study enrollment been larger, this trend would be even more significant,” Penson added in a statement released by AUA.

When preliminary results of the study were presented to the AUA annual meeting in 2011, Wilt said more than 5,000 men across multiple centers were approached to participate in the trial, but 4,300 declined, usually because they did not want their treatment determined by randomization.

He noted, however, that PIVOT is the largest randomized trial ever conducted to compare surgery with watchful waiting.

According to the study, of men with PSA levels greater than 10 ng/mL, 5.6% in the surgery group died, compared with 12.8% of those in the observation group. Fewer deaths from prostate cancer also occurred among men treated with surgery who had high-risk prostate cancer, classified as a PSA level above 20 ng/mL and a score of 8-10 on the Gleason scale, a measure of tumor aggressiveness. In this subgroup, 9.1% of men who had surgery died, compared with 17.5% for observation.

In addition to its size, the PIVOT study also is criticized because it began gathering data early in the PSA era, when testing was less universal and more likely to be prompted by symptoms. In fact, only 40% of men in the PIVOT study had low-risk prostate tumors, defined as a PSA level of less than 10 ng/mL or a Gleason score of less than 7. Currently, more than two-thirds of prostate cancers detected by PSA tests are considered low-risk.