Breast cancer is the leading cause of cancer in women accounting for 30% of all cancers, affects 1 in 8 women, and is the second most common cause of cancer mortality. The size of the cancer at the time of diagnosis has been shown to be the single most important prognostic factor that determines disease outcome. The role of screening mammography is to detect cancer early in the preclinical phase where the chance of cure is the highest. The incidence of breast cancer has been rising in the recent decades, and multiple randomized clinical trials and other studies evaluating the efficacy of screening for breast cancer with mammography have conclusively and overwhelmingly proven thebenefitof screening mammography in reducing mortality from breast cancer. About 1 in 8 U.S. women (12 %) will develop invasive breast cancer over the course of a lifetime. In 2019, an estimated 268,600 new cases of invasive breast cancer are expected to be diagnosed in women in the U.S., along with 62,930 new cases of non-invasive (in situ) breast cancer.
About 41,760 women in the U.S. are expected to die in 2019 from breast cancer, though death rates have been decreasing since 1989. These decreases have been attributed chiefly to early detection by screening mammography as well as advances in therapy. Apart from lung cancer, death rates from cancer for women in the USA is the highest for breast cancer than from any other type of cancer. The American cancer society estimated that as of January 2019, there are more than 3.1 million women with a history of breast cancer in the U.S.
A review 14 clinical trials that evaluated the value of screening for breast cancer with mammography reported that there was a significant benefit with mortality reduction from screening mammography ranging from 24-76% (3). A review of 17 trend studies, 20 incidence based mortality studies and 8 case control studies from European studies showed a mortality rate reduction of 25-31%, but when looking at women who were actually screened a significantly greater benefit of a 38-48 % mortality rate reduction was shown