Women's Health: A Big Tamoxifen Dropout Rate
For women whose breast cancer is fueled by estrogen, the drug tamoxifen can be a lifesaver: Taking it for five years after treatment nearly halves the risk that the cancer will come back. But many who start the drug stop taking it prematurely.
Researchers from Trinity College Dublin looked at prescription records for 2,816 women older than 35 who began taking tamoxifen between January 2001 and January 2004. They discovered that more than 22 percent of the women stopped taking the drug within a year. (Five years has been established as the optimal period; taking it for a shorter time reduces its survival benefit.) After 3 1/2 years, more than a third of women were no longer taking tamoxifen. The study will appear in the March 1 issue of Cancer and was published early online.
The results tell researchers that, as oral medications for cancer become more common, there may be a need to put more emphasis on compliance. "Up until now, the main treatments have been intravenous chemotherapy, and monitoring how well people are taking that is very easy," says Thomas Barron, lead author of the study and a pharmacoepidemiologist at the Trinity Centre for Health Sciences at St. James's Hospital in Dublin. Not so with a pill taken at home.
The study didn't look at why women stopped taking the medicine, but previous research has put the blame for noncompliance on side effects–namely hot flashes and other postmenopausal symptoms. Antidepressants might be used to relieve those symptoms, but whether that would make a difference requires further research, says Barron.
It's not clear whether the rates of noncompliance would differ in the United States. The women in this study were getting free medicine because they are either over 70 or have low incomes, so presumably cost was not a reason for failing to take the drug. That might be different in a group of women who had to pay for the medicine themselves.
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