Breast cancer chemoprevention

Breast cancer chemoprevention

Chemoprevention is the use of drugs to reduce the risk of cancer. Several drugs have
been studied for lowering breast cancer risk.
Tamoxifen: Tamoxifen blocks some of the effects of estrogen on breast tissue. It has
been used for many years to reduce the risk of recurrence in localized breast cancer and
as a treatment for advanced breast cancer when the tumor is estrogen-receptor positive
(see the section, "How is breast cancer treated?").
Tamoxifen can also lower the risk of getting breast cancer in women who are at increased
risk for the disease. It seems to affect the risk of breast cancers that are estrogen
receptor−positive (ER-postive), but not those that are estrogen receptor−negative (ERnegative).
Most breast cancers that occur in women after menopause are ER-positive.
Results from the Breast Cancer Prevention Trial (BCPT) have shown that women at
increased risk for breast cancer are less likely to develop the disease if they take
tamoxifen. Women in the study took either tamoxifen or a placebo pill for 5 years. After
7 years of follow-up, women taking tamoxifen had 42% fewer breast cancers than women
who took the placebo, although there was no difference in the risk of dying from breast
cancer. Tamoxifen is approved by the US Food and Drug Administration (FDA) for
reducing breast cancer risk in women at high risk. It can be used in women even if they
haven’t gone through menopause.
Tamoxifen has side effects that include increased risks of endometrial (uterine) cancer (in
women who have gone through menopause) and serious blood clots, so women should
consider the possible benefits and risks of tamoxifen before deciding if it is right for
them.
And while tamoxifen seems to reduce breast cancer risk in women with BRCA2 gene
mutations, the same may not be true for those with BRCA1 mutations.