Tamoxifen and Breast Cancer Prevention
Few women at risk for breast cancer
willing to use drug to prevent the disease
Fewer than one in five women eligible to take tamoxifen were inclined to take the drug after being told of its risks and benefits, according to a new study.
The study, from the May 15, 2005 issue of CANCER, a peer-reviewed journal of the American Cancer Society, reports that concerns over the drug's adverse effects were the primary reason for refusal.
Tamoxifen, a synthetic estrogen receptor modulator, is an effective breast cancer adjuvant therapy and is also recognized as a breast cancer prevention drug for women. It also has the added benefit of reducing the risk of osteoporotic fractures. A recent metanalysis of existing trials calculated a dramatic 38 percent reduction in the incidence of breast cancer in women who used tamoxifen.
However, the medication is not without significant side effects, including increased risk of endometrial cancer, pulmonary embolism, painful sexual intercourse, stroke, and cataracts. These risks fuel public debate about the drug's use in preventing breast cancer, even among high-risk women.
Understanding reasons why women decline to take tamoxifen even after education provides substantial opportunities for tailoring patient education to specific groups and developing new classes of cancer prevention drugs.
Joy Melnikow, M.D., M.P.H. of the University of California, Davis and her team interviewed 255 women with significant risk factors for breast cancer. The interview included an evidence-based education session about the risks and benefits of tamoxifen and a follow-up evaluation of their knowledge about the drug and their decision to take or not take tamoxifen.
The women in the study seriously overestimated their breast cancer risk, perceiving they were at ten times their actual risk. Despite that substantial overestimation of risk, seven out of ten (70.9 percent) described their risk as low or average.
After hearing about the drug's benefits and risk, only 17.6 percent of women over 50 in the study who were potentially eligible to take it would take tamoxifen. Even among women who had heard of tamoxifen, few were inclined to try it, and very few changed their minds after the educational session.
Surprisingly, the decision to use or not use tamoxifen was independent of actual breast cancer risk. Concerns about adverse effects or low self-perceived breast cancer risk were significant reasons for not using tamoxifen. Women from low economic backgrounds or confident in its benefits to reduce breast cancer risk and prevent osteoporotic fractures were inclined to use it.
Dr. Melnikow and colleagues conclude, "the results of our study indicate that many high-risk women are unwilling to consider tamoxifen even with extensive education about its potential benefits and harms."
Article: "Preferences of Women Evaluating Risks of Tamoxifen (POWER) Study of Preferences for Tamoxifen for Breast Cancer Risk Reduction," Joy Melnikow, Debora Paterniti, Rahman Azari, Christina Kuenneth, Stephen Birch, Miriam Kuppermann, James Nuovo, Janet Keyzer, Stuart Henderson, CANCER; Published Online: April 11, 2005 (DOI: 10.1002/cncr.20981); Print Issue Date: May 15, 2005.