This story reports on results from a double-blind, placebo-controlled, randomized trial, which found that the aromatase inhibitor, exemestane, is an effective option for preventing breast cancer in higher risk, postmenopausal women. The story does a nice job of discussing the study, presenting the outcomes, and framing it as a decision to be made after weighing the potential benefits and harms. However, we would have liked to have seen a broader discussion on whether healthy women would really want to take a medication with potentially serious side effects and only a modest benefit.
There are significant side effects associated with tamoxifen and raloxifene and many women feel these potential harms outweigh the potential benefit of reducing their risk of developing cancer. Aromatase inhibitors have fewer side effects and may be a more attractive option for postmenopausal women who have an increased risk of breast cancer; however, studies have shown that a very small percentage of women in this higer risk group have any desire to take tamoxifen. It’s unclear whether aromatase inhibitors provide enough benefit to change womens’ preferences.
In addition, about half of patients using aromatase inhibitors to prevent a recurrence of breast cancer have stopped taking the drug after just 2 years, so these drugs are not without problems. One could argue that nonadherence would be even greater in healthy women taking it to prevent a first breast cancer.
According to the story, brand-name aromatase inhibitors cost between $340 and $420 a month, but the story also points out that lower-costing, generic versions are available in the U.S. It would have been useful had the story also provided cost information for the other preventive drug options, tamoxifen and raloxifene.
A particular strength of this story is its presentation of data. Dr. Winer, an independent source included in the story, translates a 65% risk reduction to mean that exemestane may reduce a woman’s risk of developing breast cancer from 3% to 1%. Not only does the story provide absolute risk, but it also presents the number needed to treat. According to the study authors, 26 women would need to take exemestane for five years to prevent a single case of breast cancer. It should be noted, however, that few women in the study completed five years of therapy.
Since this is being used as a preventive measure in healthy women, side effects are very important and data should have been provided. The story indicates that “slightly” more women taking exemastane experienced hot flashes, fatigue, sweating, insomnia, and joint pain, compared to those taking placebo pills. It would have been helpful to note, for example, that 40% in the exemestane group experienced a hot flash versus 32% in the placebo group. Citing older research, the story indicates that that joint pain, muscle aches, problems having sex, and vaginal dryness may be more evident with a longer duration of use.
The story makes it clear that the study was a large-scale, placebo-controlled, randomized trial, which enrolled over 4500 women in North America and Europe. The women included had at least one risk factor for breast cancer. It also notes that given the significant risk reduction associated with exemestane, the study was stopped after 3 years to give women in the control arm the option of taking exemestane to prevent possible breast cancers. More information regarding participants’ characteristics, including age and race would have been helpful.
This story did not engage in disease-mongering.
In addition to including experts not affiliated with the exemestane study, the story also notes that the it was funded by the Canadian Cancer Society, the Avon Foundation, and Pfizer. In addition, the writer points out that the study lead and a few other authors have received speaking fees from Pfizer and other pharmaceutical companies that make cancer drugs.
This story compares the benefits and harms of exemestane with tamoxifen; however, a mention of how these compare with raloxifene, would have been useful.
The availability of aromatase inhibitors is not in question.
It’s clear from the story that aromatase inhibitors are currently used to prevent breast cancer recurrences. It’s also clear that this is the first study evaluating its utility for preventing the first instance of breast cancer in healthy women with a higher risk of developing the disease.
The story does not appear to be based on the press release.