BEIJING, Nov. 12 (Xinhuanet) -- Hundreds of women every year are having treatments for breast cancer, including surgery and chemotherapy, that are unnecessary because nearly one-third of cancers detected by screening tests are not dangerous, new research suggests. Researchers in Australia say they have proven for the first time that breast cancer screening is responsible for substantial "overdiagnosis" of the disease.

    Experts at the University of Sydney found the overdiagnosis rate was between 30 and 42 percent, meaning that between 23 and 29 percent of women aged 50 to 69 are having cancer treatments they do not need. While previous studies have estimated overdiagnosis rates as high as 52 percent from breast cancer screening, the new study is the first to rule out other known causes of breast cancer as being an alternative explanation for the higher detection rate, which has doubled since screening began.

    (Agencies)