NCI Cancelled Breast Cancer Prevention Drug Trial
The Wall Street Journal on Tuesday examined the reasoning behind the National Cancer Institute'sdecision in June to cancel a five-year, $100 million study designed totest the new class of breast cancer prevention drugs known as aromataseinhibitors. The trials were to be conducted by the Pittsburgh,Pa.-based National Surgical Adjuvant Breast and Bowel Project, which has enrolled more than 110,000 women and men in trials of breast and colorectal cancer treatments (Parker-Pope, Wall Street Journal, 8/14).
Tamoxifen, which blocks the production of estrogen, is the only FDA-approveddrug for reducing breast cancer risk, but it increases risk for uterinecancer and blood clots. Another estrogen-blocking drug, calledraloxifene, has been shown to be equally effective as tamoxifen at reducing breast cancer risk, but it increases risk of hot flashes and other menopause-related symptoms.
Aromataseinhibitors work by blocking the production of estrogen. The study wouldhave involved administering either raloxifene or the aromataseinhibitor letrozole to 12,800 women at high risk of developing breastcancer at 500 sites in the U.S. and Canada. A committee appointed byNCI Director John Niederhuber in June decided not to endorse the study,citing the cost and questions concerning its usefulness and safety. Inaddition, the committee said that two large U.S. and England-basedstudies of the drugs are under way (Kaiser Daily Women's Health Policy Report, 6/20).
Study researchers have appealed the cancellation to NIH Director Elias Zerhouni, the Journal reports.NSABP in a letter to Zerhouni appealing the cancellation said it"represents a dangerous and unjustified departure" from NCI'straditional review process. NSABP Chair Norman Wolmark said the groupis "passionate in [its] belief this is an extremely useful trial thatwill benefit women," adding that the group "think[s] an injustice hasbeen done to women by canceling the trial."
Niederhuber hassaid that the agency's funds would be better spent on identifyingcharacteristics that indicate increased breast cancer risk instead ofgiving preventive drugs to women who might not have a high risk ofdeveloping the disease. According to the Journal, NCI also is concerned about possible side effects of the drugs.
Niederhuberin a letter to Sen. Arlen Specter (R-Pa.), who had inquired about thestudy's cancellation, said there was evidence that healthy women didnot want to take drugs to prevent breast cancer because of potentialside effects. Niederhuber added that although previous trials of breastcancer prevention drugs have provided "valuable information," they"failed to change the practice of breast cancer prevention among womenand their health care providers." Carolina Hinestrosa -- executive vicepresident of the National Breast Cancer Coalition,which supports the cancellation -- said the group is "very concernedabout the approach of treating healthy women with drugs that are toxicin order to reduce the risk for very few who benefit."
According to the Journal, letrozolelikely will not be approved for breast cancer prevention if the trialdoes not take place because such a trial likely would be too expensivefor the private sector. Some researchers said that other proposals forclinical trials of breast cancer prevention drugs are unlikely if NIHupholds NCI's decision. The journal Lancet in a recenteditorial said the cancellation was "troubling" and that an"independent investigation into how the decision was made and whetherit was made fairly is warranted." NCI declined to comment on theeditorial but said Niederhuber "got the best scientific advice andacted on it" in canceling the study (Wall Street Journal, 8/14).
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