In the 1971 study, some new clinical studies were conducted and these studies showed some effectiveness of Tamoxifen, which is used to treat breast cancer. Two years later, knowing that there was a link between estrogen and breast cancer, the success of these first clinical trials sold ICI to the United States as a treatment for breast cancer. However, FDA approval was issued many years later, in 1977.
The drug was then sold by ICI in a number of other Nolvadex countries (and ICI was subsequently renamed AstraZeneca). Nolvadex was later followed by a number of generic drugs manufactured by other laboratories, which is now too much for the list. In 1998, the FDA approved the extension of the medical / clinical use of Tamoxifen, which also included the prevention of breast cancer in women diagnosed with a high chance of developing the disease.