News outlets have recently reported that new research shows the “anti-estrogen drug Aromasin appears to cut the odds of breast cancer by 65 percent in high-risk postmenopausal women.” They report that “unlike other anti-estrogen therapies such as tamoxifen and raloxifene, Aromasin (exemestane) did not carry a heightened risk of endocrine cancer or blood clots, although it did have the well-known problems of hot flashes and joint stiffness also attributable to tamoxifen and raloxifene.”
It does seem that Aromasin cut the risk in the women studied by 65 percent after taking it for approximately three years as opposed to a 38 percent for Tamoxifen. It is important to remember that “in absolute terms, 1.4 percent of women in the placebo group developed cancer compared with about one-half of 1 percent of women taking the drug.” That means that in a group of 1000 women, 9 fewer would get cancer. They project that this figure should improve after using the drug for five years. No study can yet verify this. At this point, even women who are using the drug for prevention of breast cancer recurrences or metastases after having invasive breast cancer do not take the drug longer than five years
My concern with the study is twofold. First, Aromasin is a drug with many side effects. While it is true that it does not cause blood clots or endocrine cancer, its side effects include fatigue, nausea, hot flashes, depression, bone pain, insomnia, anxiety, and shortness of breath, among many other less frequent side effects. Even many women with breast cancer who have major incentives to continue taking this drug are unable to continue taking it. I was one of them. Do women really want to risk such side effects as a possible preventative for breast cancer?
My second concern is the fact that the only “risk factor” that 49 percent of these women had was the fact that they were 60 years or older. I do not believe that makes them at “high risk.” It makes them at normal risk for their age group. For these women, in particular, it seems quite drastic to me to take Aromasin as a preventative. Women with well-known risks for breast cancer such as BRCA 1 and 2 were excluded from this study.
It is interesting to note that this study (called Map.3) initially had a third arm which included taking Aromasin plus Celebrex in addition to the placebo arm and the Aromasin arm. This third arm was stopped because of concerns for “cardiovascular safety with Celebrex. I presume they started with this arm because of the well-known problems with bone and joint pain when using Aromasin.
Mary Miller- Breast Cancer Profile in Courage
“A drug now used to prevent recurrences of breast cancer can also reduce the risk of it occurring in the first place, providing a new option for women at high risk of getting the disease, researchers reported here on Saturday.
Two drugs, tamoxifen, and raloxifene are already approved to prevent breast cancer but both are rarely used for that purpose, in part because they can have serious side effects like blood clots. The researchers said the new option, exemestane, does not have those side effects and might be more acceptable…
So researchers have long suspected that aromatase inhibitors would also reduce the risk of an initial occurrence of breast cancer, though this is the first big randomized study to demonstrate that…
After a follow-up of about three years, 11 women getting the drug had developed invasive breast cancer compared with 32 of the women receiving a placebo. That is a reduction in risk of 65 percent.
But in absolute terms, 1.4 percent of women in the placebo group developed cancer compared with about one-half of 1 percent of women taking the drug.
About 94 women would have to be treated for three years to prevent one case of breast cancer, Dr. Goss said. In the trial, exemestane side effects were acceptable, he said. But women who took exemestane had more hot flashes and arthritis than those who had the placebo.
Still, whether exemestane will catch on where the other drugs have not remains to be seen.
Some doctors and patient advocates said that aromatase inhibitors had known side effects like bone pain and joint pain that caused many women who already had had cancer to stop taking them. For healthy women, that would be an even harder sell…