Have you even read that Wikipedia article that you yourself linked?

The World Health Organization, the Canadian Task Force on Preventive Health Care, and many other scientific organizations recommend against the use of breast self-examinations.[11] Also, the Royal Australian College of General Practitioners states that teaching women to perform breast self-examination is no longer recommended.[12] In the US, however, there is no consensus among organizations related to breast self-examination as the American College of Obstetrics and Gynecology, and the American Medical Association recommend monthly breast self-examination while the American Cancer Society, the National Cancer Institute, the US Preventative Services Task Force, and the National Comprehensive Cancer Network neither recommend nor discourage breast self-examination.[13]