Breast Cancer Drug Study Canceled

By Rob Stein
Washington Post Staff Writer
Wednesday, June 20, 2007

The federal government yesterday canceled a $100 million study designed to test a new generation of drugs to prevent breast cancer in women at risk for the disease.

The National Cancer Institute took the unusual step of terminating the long-planned study, saying the massive project could not be justified amid questions about the study's usefulness and the drugs' safety.

"The numerous scientific concerns . . . are sufficiently formidable that the NCI will not commit to the funding of this particular trial," the agency wrote. "While the . . . study may provide another possible option for women at risk for breast cancer, the dangers of introducing these drugs, with their many known side effects, outweighs their potential until we are better able to determine who will benefit from these interventions and what the longer term effect may be."

The decision was criticized by proponents, who argued that the study would have been crucial to determining the best drugs to prevent breast cancer, potentially protecting thousands of women from the common malignancy.

"We're certainly disappointed," said D. Lawrence Wickerham of the National Surgical Adjuvant Breast and Bowel Project in Pittsburgh, which was organizing the study. "We feel this trial is scientifically valid and one that has the potential to impact the health of thousands of women in this country and around the world."

The planned study had divided breast cancer researchers and patient advocates.

About 180,000 U.S. women are diagnosed with breast cancer each year and about 40,000 die from it, making it the second most common cancer in women and second leading cause of cancer deaths in women. At least 1 million women are at high risk for the disease because of family history, having a gene that increases their risk or other reasons.

The only drug approved to reduce the risk is tamoxifen, which blocks the hormone estrogen. But because tamoxifen increases the risk for uterine cancer and blood clots, few women take it unless they have already had breast cancer. Another estrogen-blocking drug, called raloxifene, appears equally effective with fewer serious side effects, but it has also not been widely adopted in part because it can cause hot flashes and other symptoms similar to those of menopause.

The study was intended to evaluate a new generation of drugs known as aromatase inhibitors, which appear to be more effective at reducing the risk. The study would have involved giving either raloxifene or the aromatase inhibitor letrozole to 12,800 women at high risk for breast cancer at 500 sites across the United States and Canada and then following them for five years.

After multiple reviews, the cancer institute had initially endorsed the trial. But amid budget concerns, NCI Director John Niederhuber in January called for a new review, citing scientific questions about the project.

A committee Niederhuber appointed decided last week not to endorse the project, citing its cost and the fact that two large studies comparing other aromatase inhibitors with a placebo were underway in the United States and England and would provide answers before the federal trial would be completed. The committee also questioned how many women would use an aromatase inhibitor even if it was shown to be effective. Aromatase inhibitors carry risks, particularly of brittle bones.

Although some breast cancer advocacy groups had endorsed the study, others had lobbied against it, saying more research was needed to better identify women who would benefit most from such drugs, particularly because of the side effects.

"We're talking about giving very powerful drugs to healthy women who have not had breast cancer," said Barbara Brenner of the group Breast Cancer Action. "We know there are lots of side effects in the short term. We have no idea what they would do in the long term."

Others disagreed, saying women should have the choice.

"A woman who is very high risk for breast cancer wants to see if she can do something to prevent it. She should have that option," said Pat Halpin-Murphy of the Pennsylvania Breast Cancer Coalition.

© 2007 The Washington Post Company