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.
