In a study involving 88 women at high risk of eventually developing breast cancer, only 1 agreed to take tamoxifen, a drug that can reduce the risk of the cancer in high-risk women by nearly 50 percent, according to a review of studies on the topic.

Furthermore, only about half of women discussed tamoxifen with their doctors - and in most cases their doctors advised against taking the drug.

Nearly all the women said they chose not to take tamoxifen because of a fear of side effects, which can include hot flashes and other symptoms of menopause, Blood clots in the legs or lungs, Stroke, and uterine cancer, said study author Dr. Rebecca Taylor of the University of Ottawa in Ontario, Canada.

However, these risks are “small in magnitude,” she said; uterine cancer is caught at an early stage and is “very curable,” relative to breast cancer.

“I think there are a small group of women who would benefit from tamoxifen and I think for these women it is important to provide them with accurate information, because fear of side effects or uninformed advice could lead to a premature decision not to take tamoxifen,” Taylor said.

A 2003 study estimated that 2 million women living in the US would likely benefit from taking tamoxifen, which could prevent 1 million cases of breast cancer over the following 5 years.

However, given the risk of side effects from tamoxifen, experts recommend that women at high risk of breast cancer should discuss tamoxifen with their physicians, to weigh the potential risks and benefits of taking it to prevent cancer.

To investigate the outcome of those conversations, the researchers followed 88 cancer-free women assessed as being at high risk because of age, family history and other factors.

Each of the women received letters telling them their chances of getting breast cancer in their lives and within the next five years, and encouraging them to talk to their family doctors about tamoxifen.

Each woman’s family physician also received a letter explaining she was a candidate for tamoxifen. A few months after sending the letters, the researchers called the women and asked them if they had discussed tamoxifen with their doctors.

Forty women said they had never discussed tamoxifen with their doctors, the authors report in the Annals of Family Medicine. Of the 48 who consulted their doctors, only 3 doctors recommended the drug, and only 1 woman started taking it.

Along with fear of side effects, many women said they declined tamoxifen on their doctors’ advice, and because they believed they still had a low risk of breast cancer.

Taylor explained that a woman is defined as “high risk” if she has at least a 1.66 percent estimated chance of developing cancer in 5 years.

“If you think about this another way, that means that the same woman has a 98.33 percent chance of not getting breast cancer in the next five years,” Taylor said. “Most women think that sounds like a pretty low risk.”

SOURCE: Annals of Family Medicine, May/June 2005.