Nolvadex Mechanism of Action

Nolvadex has been used for over three decades for the treatment and prevention of breast cancer in female patients. This medicine has been approved by the FDA for this purpose and may need to be taken for up to 5 years. The exact mechanism of action is not known, but the effects of Nolvadex have to do with the fact certain hormones, estrogen and progesterone, are known to stimulate certain types of cancers to grow. These hormones are produced in the ovaries and certain other tissues. Hormone-sensitive breast cancers can grow because the levels of these hormones reach a specific level, which may be individual for every patient.

Nolvadex is thought to somehow block the effects of estrogen on the growth of breast cancers. Being a selective estrogen receptor modulator that binds to estrogen receptors and acts as an estrogen antagonist, it prevents hormone receptors present on hormone-sensitive cancer cells from being activated. Since early breast cancers are mainly estrogen positive, Nolvadex can also be used to prevent them from developing. Nolvadex therapy demonstrated high efficiency in a series of trials, with postmenopausal patients taking Nolvadex for 5 years being 50% less likely to develop the disease (all patients were from high risk groups for breast cancer).