Tamoxifen is given to breast cancer patients to suppress estrogen or both estrogen & progesterone?

Estrogen. Tamoxifen is given to individuals with specific breast cancers that are driven to grow by the presence of estrogen receptors. Tamoxifen interferes with the activity of estrogen in the breast, preventing cancer growth. The role of Progesterone receptors is unclear, though Progesterone receptors in breast cancer are generally associated with estrogen receptors, making tamoxifen an effective therapy.
Estrogen. Tamoxifen is an anti- estrogen in the breast, but can act like estrogen in other organs, notably the uterus. Women on tamoxifen, who have not had a hysterectomy, need to have a gyne keep a close eye on uterine health.
It's complicated. Tamoxifen is a selective estrogen receptor modulator which competes with estrogen to block this receptor on cancer (and other) cells. It does not suppress production of either estrogen or progesterone. Ironically, it is effective against breast cancer cells that harbor either the estrogen or Progesterone receptors (although, tumors that are estrogen rec. (-) and Progesterone rec.(+)are rare.).

Related Questions

If I have too much estrogen, or not enough progesterone, does that make me more susceptible to breast cancer?

Breast cancer risk. Maybe: some breast cancers take up estrogen as a sort of growth hormone to encourage growth, so too much estrogen can speed growth of these cancers. There is a very small increase in breast cancer risk with estrogen only given postmenopausally for the symptoms. Relative increase in Progesterone only is associated with some breast disorders also but cancer risk is unclear. Read more...
High E2/Prog is NG. A high estrogen/progesterone ratio is a contributing factor to many medical and metabolic problems. Breast, ovarian, cervical cancer, pms. High e2/prog ratio will activate your parasympathetic nervous system and cause symptoms from excess vagal stimulation. Have your doctor check your e2 and prog during mid luteal phase of your menstrual cycle (day 18-21). Read more...

Hormone replacement therapy. Estrogen alone increases risk of uterine cancer. Adding progesterone increases risk of breast cancer, but reduces risk of uterine cancer. What's the right balance?

Individual. Yes, estrogen alone does increase the risk of uterine cancer over time. And yes the whi showed that the combination of a certain synthetic estrogen and a certain synthetic progestin increased the risk of breast cancer. But most specialists do not use those older types of synthetic hormones and with newer medications the risks are lower and different. So a balance can be achieved. Read more...

Are the risks of getting cancer (especially breast cancer) higher, if I am already on hormone treatment (estrogen and progestogen) at age 17?

Family practice . Tell us why you are on hormone replacement therapy. Did they remove both ovaries or are they nonfunctional. Not higher risk for breast cancer. Slightly higher risk for blood clots. Don't smoke and exercise regularly. Read more...
No. Hormone use as birth control is not felt to increase the risk of developing breast cancer. It is the use of hormone replacement after menopause that is the concern. Read more...

When do breast cancer patients need tamoxifen?

Tamoxifen. A selective estrogen receptor modulator is effective added therapy for women with well-differentiated, estrogen receptor positive breast cancers. Read more...
Estrogen receptor +. Tamoxifen is only indicated for estrogen receptor positive breast cancers. Read more...

How long would I have to take estrogen before I start worrying bout breast cancer.?

5 yrs or less. It has been shown that using hormone replacement therapy (hrt) can increase one's risk of breast cancer when taken for longer than 5 years. Because of this we no longer recommend taking hormones for long periods of time. Work with your gynecologist for options to deal with the symptoms of menopause. Read more...