Panel Urges Renewed Testing of Breast Cancer Drug

An advisory panel to the Food and Drug Administration voted Tuesday to let stalled clinical trials of the anti-breast cancer drug tamoxifen resume without major changes, despite growing evidence that the drug raises the risk of uterine cancer.

Previous studies have shown that tamoxifen reduces the risk of a recurrence of breast cancer by 40%. In the new trial, which was suspended recently following concerns about the accuracy of data, researchers are trying to discover if it can prevent breast cancer from occurring in the first place.

The new test is controversial because the drug is being given to healthy women, not those already diagnosed with breast cancer. Those chosen for the project have twice the normal risk of developing breast cancer as determined by such factors as family history and age.

But tamoxifen appears to carry a higher risk of causing uterine cancer than was understood when the FDA first approved the Breast Cancer Prevention Trial in 1991.

The tamoxifen prevention study is one of several massive breast cancer trials in the Pittsburgh-based National Surgical Adjuvant Breast and Bowel Project, which was ordered to stop enrolling new patients in March after revelations that a Canadian researcher had submitted fraudulent data in one of the breast cancer studies. Almost 11,000 of the proposed 16,000 subjects in the $68-million study have signed up since 1992.

At a hearing before Tuesday’s advisory vote to resume the trial, representatives of the National Cancer Institute estimated that the drug would prevent 133 cases of breast cancer in 8,000 women who would receive the drug.

Cancer institute researchers also estimated that 83 or more patients would develop endometrial cancer--cancer of the uterus lining--and many more would develop other problems of the uterine lining that might lead to surgical procedures.

The institute has proposed additional diagnostic help for tamoxifen patients and new studies on the uterine effects of tamoxifen.