December 12, 2013
Reducing Risk Of Breast Cancer With Promising New Drug Treatment
Rebekah Eliason for redOrbit.com – Your Universe Online
There is good news for postmenopausal women who are at high risk for developing breast cancer. According to a new study, taking the drug anastrozole for five years reduced the likelihood of developing the disease by 53 percent when compared with women who took a placebo.
Approximately 80 percent of women in the United States who are diagnosed with breast cancer have tumors that contain high levels of hormone receptors. These types of tumors are fed by the hormone estrogen. Using drugs to prevent estrogen production in the body is considered an effective treatment for this type of cancer. This study was researching the effectiveness of the drug anastrozole in treating postmenopausal women with hormone receptor-positive breast cancer. Anastrozole has been used to treat breast cancer for over ten years.
“We initiated the International Breast Cancer Intervention Study II (IBIS-II) Prevention trial to investigate whether anastrozole can be used effectively to prevent breast cancer. Our initial results show that for postmenopausal women who do not have breast cancer, but are at high risk for developing the disease, anastrozole reduced breast cancer incidence by 53 percent with very few side effects,” said Jack Cuzick, PhD, chairman of the IBIS-II Steering Committee.
Cuzick also explained, “Two other antihormone therapies, tamoxifen and raloxifene, are used by some women to prevent breast cancer, but these drugs are not as effective and can have adverse side effects, which limit their use. Hopefully, our findings will lead to an alternative prevention therapy with fewer side effects for postmenopausal women at high risk for developing breast cancer.”
The double blind study spanning from 2003 to 2012 consisted of 3,864 participants who were postmenopausal women with increased risk for developing breast cancer. Randomly 1,920 women were selected to take the drug anastrozole for five years while the other 1,944 were given a placebo.
To be considered at high risk, women were required to meet one of the following criteria: having two or more blood relatives with breast cancer, having a mother or sister who developed breast cancer before she was 50 years old, or having a mother or sister who had breast cancer in both breasts.
A median follow-up was performed just after five years. Researchers were excited to discover that the participants who took anastrozole were 53 percent less likely to develop breast cancer compared to those who took the placebo. According to Cuzick, there were only a minimal amount of side effects reported, which included small increases in muscle aches and pains and hot flashes.
“We are planning to continue following the IBIS-II Prevention participants for at least 10 years, and hopefully much longer,” said Cuzick. “We want to determine if anastrozole has a continued impact on cancer incidence even after stopping treatment, if it reduces deaths from breast cancer, and to ensure that there are no long-term adverse side effects.”
This study was presented at the 2013 San Antonio Breast Cancer Symposium, held December 10-14. Simultaneously, this study is being published in journal The Lancet.