As goes PSA testing for prostate cancer, so goes mammography for breast cancer. A new study published in the Archives of Internal Medicine suggests that the great majority women who find breast cancer as a result of regular screening have not had their lives saved by the test. But, as Tara Parker-Pope reports in the New York Times Well column, many have had their lives diminished by unnecessary treatment. Two Dartmouth researchers, Dr. H. Gilbert Welch and Brittney A. Frankel, estimated a woman’s 10-year risk of developing breast cancer and her 20-year risk of death, factoring in the added value of early detection based on data from various mammography screening trials as well as the benefits of improvements in treatment. Among the 60 percent of women with breast cancer who detected the disease by screening, only about 3 percent to 13 percent of them were actually helped by the test. It’s true: the researchers believe that of the 138,000 women found to have breast cancer each year as a result of mammography screening, 120,000 to 134,000 are not helped by the test. That’s because of the truly deadly cancers that are caught by screening, only a small fraction are caught at the moment when treatment can help. Parker-Pope reports that clinical trial data suggests that 1 woman per 1,000 healthy women screened over 10 years falls into this category, although experts say that number is probably even smaller today because of advances in breast cancer treatments. Read more in the New York Times.