Tamoxifen is one of the most commonly used medications to treat women with breast cancer, and has been for many years. Now, new research findings may make doctors and patients think twice before choosing tamoxifen to prevent a recurrence of breast cancer.
According to a study from the Fred Hutchinson Cancer Research Center and published in the journal Cancer Research, tamoxifen may protect against the recurrence of some types of breast cancer, but it may also increase the risk of some particularly aggressive and deadly breast cancers, especially when used long term.
Tamoxifen blocks the action of the hormone estrogen, which can stimulate cancer growth in breast tissues. It can reduce the risk of getting a second breast cancer by 50 percent.
Women who use tamoxifen often suffer from side effects such as hot flashes and vaginal dryness, which are symptoms of estrogen deficiency. Rarer but more serious side effects can include blood clots, strokes, cataracts and uterine cancer. Because tamoxifen is one of the few drugs that has been shown to significantly reduce the risk of recurring breast cancer, doctors and patients often decide that the benefits of the drug outweigh the risks.
Tamoxifen is used to prevent a recurrence of estrogen receptor-positive breast cancers, and does reduce the risk of having those types of cancers recur. However, researchers found that the risk of getting a more aggressive and deadly type of estrogen receptor-negative type of breast cancer is increased in tamoxifen users by 440 percent.
According to the study’s lead author, Christopher Li, M.D., Ph.D., “It is clear that estrogen-blocking drugs like tamoxifen have important clinical benefits and have led to major improvements in breast cancer survival rates. However, these therapies have risks, and an increased risk of ER negative second cancer may be one of them.” In a video on the Hutchinson website, Li explained that doctors and patients should consider this new research when weighing the risks and benefits of using tamoxifen long term.
For more info:
Fred Hutchinson Cancer Research Center
What Your Doctor May Not Tell You about Breast Cancer – Introduction
Nolvadex (tamoxifen) Prescribing Information
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