The authors of an European study assert that while screening may reduce cervical and colorectal cancer mortality, it's not so for breast cancer" [BMJ July 28, 2011]

Three poignant cases where over-supply (of docs) means over-testing or over-treating

Screening for Drug Use -- 1 Question

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."