For the study, published in the August 15 issue of Cancer Research, researchers looked at data from 1,207 men who were diagnosed with prostate cancer between 1982 and 2004 and determined their Gleason grade—an assessment that looks at tumors at the cellular level and is one of the best predictors of prostate cancer prognosis. It differs from cancer stage, which measures roughly how much cancer has spread, and how large and invasive a tumor is, says study author Kathryn L. Penney, Sc.D., an instructor in medicine at Harvard Medical School and associate epidemiologist at Brigham and Women’s Hospital. After dividing the men into groups based on pre- and post-PSA screening era, they found that the number of late-stage cancers decreased to just 3% of men in the later period, compared to 19.9% in the pre-PSA testing group. Despite the dramatic drop in stage at diagnosis, there was only a moderate decrease in high Gleason grade cancers between the groups, from 25.3% to 17.6%. This led the researchers to conclude that Gleason grade isn’t something that progresses like stages, but is predetermined by a tumor’s characteristics. Many men with low-grade cancers choose active surveillance as their treatment, which means they don’t immediately have radiation or surgery, but instead see their doctors for regular appointments and additional PSA tests. “We think this will help men who have low-grade disease who have chosen active surveillance as their treatment feel more comfortable with their decision, knowing that their low-grade disease isn’t going to progress to a more high-grade disease,” says Penney. More from Prevention: Prostate Cancer Testing—Simplified Is His Prostate Cancer Treatment Risky and Unnecessary? Could Where You Live Determine Your Cancer Risk?
