Citing the ineffectiveness of Tamoxifen in certain patients, a panel told the Food and Drug Administration that the drug should carry a new label warning consumers of the risk of recurrence. The panel found that some patients with estrogen-related breast cancer are not as responsive to Tamoxifen. The panel has only offered its recommendations to the FDA, and any action to change the labels must be approved by the FDA at large.
Scientists believe the risk of recurrence relates to poor enzyme activity in certain women. <"http://www.yourlawyer.com/topics/overview/tamoxifen">Tamoxifen is used to block the production of estrogen–and therefore control the growth of tumors. However, a certain enzyme, CYP2D6, is required to metabolize the drug so that it can perform its intended goal of estrogen reduction. In women with deficiencies of that enzyme, Tamoxifen has been proven to be less effective in preventing a recurrence of the disease.
For women who are pre-menopausal, Tamoxifen appears to be the only treatment alternative. However, for post-menopausal women, there have been several newer drugs approved, known as aromatase inhibitors, that may be more successful in the treatment and prevention of the disease. Some medical professionals and researchers have suggested that genetic testing should be part of the decision process, in order to ascertain whether the prospective patient falls into the at-risk category. There is a possibility that the FDA will add that piece of advice to the warning labels as well. The study is yet another piece of evidence that highlights the potential importance of genetic predisposition with regard to the treatment and prevention of cancer.
Additionally, there have been previous studies linking the use of antidepressants and the effectiveness of tamoxifen. Tamoxifen drug was originally approved by the FDA in 1977.