With 20 years' experience screening for breast and prostate cancer, since screening began, 1) these cancers seemed to be more prevalent.  2) Relatively speaking the cancers are presenting at an earlier stage.  3) The "incidence of regional cancers has not decreased at a commensurate rate."   "One possible explanation is that screening may be increasing the burden of low-risk cancers without significantly reducing the burden of more aggressively growing cancers and therefore not resulting in the anticipated reduction in cancer mortality. To reduce morbidity and mortality from prostate cancer and breast cancer, new approaches for screening, early detection, and prevention for both diseases should be considered."

Esserman L, Shieh Y, Thompson I. "Rethinking Screening for Breast Cancer and Prostate Cancer." JAMA. 2009;302(15):1685-1692.