Starting in 1993 and ending in 2001, ten academic medical centers in the United States screened 76,685 men and 78,216 women for prostate, lung, colorectal and ovarian cancers. The question was whether yearly screening could catch cancers early and thus decrease mortality from these diseases. Fifteen-year follow-up results focusing on prostate cancer show little difference in mortality between men screened annually and the control group, some of whom chose to be screened occasionally. According to researchers, the results don’t necessarily negate the value of prostate cancer screening, but imply that within the data of this massive trial are clues that inform personalized decisions for subsets of this prostate cancer population.