In men with PSA levels of 10 ng/mL or less, the difference in absolute risk for all-cause mortality was 2.7%, in favor of observation.
Among men whose PSA levels were greater than 10 ng/mL, those randomized to receive radical prostatectomy had a statistically significant 13.2% absolute reduction in all-cause mortality compared with the watchful waiting group, which means that "about 8 men would have to be treated to prevent 1 death in about 12 years," he said after the meeting.
The men enrolled in the PIVOT trial are different from those in the SPCG-4 for various reasons, Dr. Wilt noted. For one, the majority of patients in the Scandinavian trial were diagnosed through palpable tumors or significant urinary obstruction symptoms. "So they had more advanced disease, even though it was still considered clinically localized," he said.
While the PIVOT enrollees are more representative of men being diagnosed and treated in the United States, there still are differences between the early era of PSA testing – the mid-late 1990s, when many of the PIVOT participants were enrolled – and current times, when "nearly all men, for better or for worse, are getting multiple PSA tests and having smaller tumors found earlier," he said.
"The risk of overdiagnosis in the PIVOT study is high, and it’s much higher today," Dr. Wilt said after the meeting. "As we move further and further to finding smaller and smaller tumors that have a very good long-term prognosis even with no treatment ... the risk of overdiagnosis becomes even greater than what we [see in PIVOT.]"
This study was supported by the Department of Veteran Affairs, the Agency for Healthcare Research and Quality, and the National Cancer Institute. Dr. Wilt reported that he had nothing to disclose.