Researchers have found that prostate cancer aggressiveness may be established when a tumor is formed and not change with time, according to a study published in Cancer Research.
After the introduction of widespread prostate-specific antigen (PSA) screening, the number of patients diagnosed with advanced-stage cancers dropped more than 6-fold in 22 years, but the percentage of patients with tumors of high Gleason grade did not change significantly. The finding suggests that low-grade prostate cancers do not change to higher-grade disease over time.
The study adds more evidence to the argument for the active surveillance of patients with low-grade prostate cancer versus treating these patients right away. Lead author Kathryn Penney, ScD, instructor in medicine at Harvard Medical School in Boston, Massachusetts, and her colleagues used data from 420 patients recruited to the Physicians' Health Study and 787 participants recruited to the ongoing Health Professionals Follow-Up Study. All patients were diagnosed with prostate cancer between 1982 and 2004 and treated with surgery. Investigators then reanalyzed prostate tissue collected from these patients to assess Gleason grade.
Four different time periods were analyzed to represent the pre-PSA and post-PSA screening eras. The percentage of patients who had undergone PSA screening increased from 42% in 1994 to 81% in 2000. In addition, the number of late-stage cancers decreased from 19.9% for the period between 1982 and 1993 to 3% between 2000 and 2004, which reflected the 85% drop in stage at diagnosis.
Researchers also found that the moderate drop in the number of tumors of high Gleason grade was not because screening prevented progression to more aggressive disease; rather, the increased diagnosis of low-grade disease would not have occurred without PSA screening.
Dr. Penney concludes that men with low-grade disease at the time of diagnosis should seriously consider discussing active surveillance with their physicians.