Tamoxifen for hormone-positive breast cancer

Tamoxifen is the oldest and most familiar drug from the group of selective estrogen receptor modulators. It is indicated for hormone-positive breast cancer in women in both premenopausal and postmenopausal women. Tamoxifen is taken as a rule for 5 years. However, with the metastatic spread of breast cancer, tamoxifen takes as long as its effectiveness continues.

Tamoxifen is indicated to reduce the risk of breast cancer in women:

  • With a high risk of breast cancer, but not suffering from this disease before.
  • Suffering non-invasive hormone-positive breast cancer (ductal carcinoma in situ).
  • Suffering invasive hormone-positive breast cancer at any stage.

Tamoxifen has very weak estrogenic activity. Getting into the bloodstream, it spreads throughout the body. In the presence of cancer cells with estrogen receptors, it combines with them and does not allow it to interact with natural estrogen. Since tamoxifen has a very weak estrogen effect, it has very little stimulatory effect on cells. And by blocking free estrogen receptors on the surface of cancer cells, it suppresses the stimulating effect of hormones on the tumor.

Thus, tamoxifen acts as an antiestrogen. It should also be noted that tamoxifen can block estrogen receptors in healthy breast cells. This effect makes it possible to use this drug in order to prevent abnormal cell growth and thus serves as prevention of the occurrence of breast cancer.

In addition, by blocking estrogen receptors, tamoxifen helps reduce the risk of developing breast cancer in women at high risk of this tumor, who did not suffer from cancer. In addition, in patients who have had breast cancer, tamoxifen reduces the risk of cancer in another gland.

When tamoxifen is no longer effective

Unfortunately, the anti-estrogen effect of tamoxifen decreases with time. After all, tamoxifen no longer has the necessary effect on breast cells. Sometimes it can even act like real estrogen, exerting a stimulating effect on the cells, rather than suppressing them.