Not only have we made great strides in treating women with breast cancer but today women, who have a high risk of the disease, are much better off thanks to pharmaceutical breakthroughs. McLeod Oncologist Dr. Michael Pavy describes the new hope for women at high risk of breast cancer:
Here are the highlights of Dr. Pavy’s comments:
Breast cancer has a hormonally driven engine in it. The female hormones – estrogen and progesterone – tend to stimulate the growth of breast cancer cells. That’s one of the reasons we’ve seen how the use of a post-menopausal progesterone-estrogen combination can sometimes increase the risk of breast cancer.
Back in the 1970s, they made a drug that is an anti-estrogen called Tamoxifen. This drug actually blocks the effects of estrogen in the body and in breast cancer cells.
We had used it in women who had breast cancer, but we wondered if women who had a high risk of developing breast cancer would be protected by Tamoxifen.
About 16 years ago, we had a large study across the United States that McLeod participated in, where we studied about 7,000 women. We selected these women as being high risk, based on a computerized model – called a GAIL model, using such criteria as their age, and when they first started their menstrual periods. There’s another one called the IBIS Cancer Tool. A woman can enter her information, answer all the questions and see her risk of breast cancer.
If a woman is high risk, she could be a candidate for Tamoxifen. Based on the study in 1999 we determined that women who took Tamoxifen for five years experienced a 50% reduction in breast cancer while on Tamoxifen. And, in following these women since then, the difference has lasted now for 16 years, giving them a prolonged decrease in breast cancer. Not only did they get help in the five years they were taking Tamoxifen, but they also got help for more than 10 years after that.
At McLeod, we also participated in another study with a drug called Raloxifene, a sister drug of Tamoxifen. Those results were found to be beneficial also. Since those two studies there have been a number of other studies and today there are 4 drugs available to high-risk women, depending on whether they are premenopausal or postmenopausal including Arimidex and Exemestane which have both been proven to be useful. We have also learned that Exemestane gives post-menopausal women a 68% reduction in their incidence of the cancer.
In addition, we have a number of things we can do for high-risk women, who have a sister or mother who has breast cancer. These women should discuss their medical history with their primary care physician or GYN physicians. If there are any questions, they can be referred to oncologists and we can counsel them on genetic testing.
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