Physicians, Women Urged to Discuss Breast Cancer Drugs 

Earlier this month a group of experts recommended that clinicians start discussing the pros and cons of tamoxifen and other prescription drugs to reduce the risk of breast cancer with women who have a high likelihood of developing the disease.

At the same time, the US Preventive Services Task Force, an independent panel of experts sponsored by the Agency for Healthcare Research and Quality (AHRQ), recommended that women at low or average risk for breast cancer refrain from taking the drugs.

The recommendations were based on a study concluding that tamoxifen and raloxifene appear to reduce the risk of developing breast cancer in women at high risk. Both the study, conducted by researchers at the University of North Carolina and RTI International, and the recommendations appeared in  recent issue of the Annals of Internal Medicine.

"Most of us in the breast cancer field have already been discussing tamoxifen with our high-risk patients," says Dr. Bert Petersen, a surgical oncologist and director of the family risk program at Beth Israel Medical Center in New York City.

Tamoxifen is the only medication approved by the US Food and Drug Administration (FDA) for prevention of breast cancer in women at high risk. So far, raloxifene is approved only for the prevention and treatment of osteoporosis, although an effect on breast cancer risk was noted in the osteoporosis trial.

"We're waiting to see the results of the STAR trial [the Study of Tamoxifen and Raloxifene, an ongoing trial by the National Cancer Institute]," Petersen says. "Pending results of the STAR trial, ralixofene may prove to be yet another drug we have in our armamentarium to reduce breast cancer risk but at this time, it's premature to start discussing it as a breast cancer reduction drug. One has to keep in mind that while it did show a reduction, that finding came out of a study that was not designed to look at breast cancer. We need to keep an open mind that it might not pan out to be that way."

Tamoxifen Use Should be Evaluated on a Case-By-Case Basis

The task force is also emphasizing that the drug be recommended on a case-by-case basis. "We're making population-based recommendations, so we're saying these recommendations are good for this group of women that are at high risk for breast cancer and low risk for complications," says Janet Allan, vice chair of the task force and dean of the School of Nursing at the University of Texas Health Science Center in San Antonio. "It doesn't mean that it necessarily fits the individual woman. That's why we are recommending not that women take this drug, but that they talk to their clinician about it."

The authors reviewed four studies, three involving tamoxifen and one involving raloxifene. The largest of the tamoxifen studies, conducted in the United States and involving 13,000 women, found a 47 percent reduction in the risk of breast cancer in women with a greater-than-average chance of developing the disease.

"It was really clear from the large [tamoxifen] study that it had a tremendous impact on reduction of breast cancer risk, and that was the largest study and probably the highest quality of the three," Allan says. "It was so impressive we certainly felt the evidence was strong enough to make recommendations, which we did."

Potential Side Effects

Both drugs also have potentially dangerous side effects: They can increase the risk of blood clots in the legs and lungs as well as cause hot flashes.

Tamoxifen may contribute slightly to the risk of stroke and of endometrial cancer. In fact, the FDA last week announced that it would be adding a "black box" warning to the labeling of tamoxifen alerting patients about the possibility of developing uterine sarcoma, a rare but dangerous cancer of the uterus.

"There's enough harm to it and benefit that a woman who is at high risk or who considers herself at high risk needs to go over the evidence to make a decision," Allan says.

Women with previous blood clots, hypertension, or diabetes should avoid the drugs, as should women who are not at high risk for breast cancer.

"We're saying that this is a drug based on a very good study that looks like for certain women it's going to make a big difference," Allan says. "We haven't had much to offer women who are at risk. This is another piece. But what we don't know is if women take this for five years, is that enough or will they have to take it longer or will they have to go off it for a while and go back on? We still need future studies."

Always consult your physician for more information.