Prevention trials with tamoxifen may be delayed in USBMJ 1994; 308 doi: https://doi.org/10.1136/bmj.308.6940.1318 (Published 21 May 1994) Cite this as: BMJ 1994;308:1318
- J Roberts
A North American trial to establish whether the antioestrogen drug tamoxifen effectively prevents breast cancer is being threatened with delay because of fears that the drug may be too dangerous for the purpose. The study is being administered by the same group that ran a controversial trial of lumpectomy.
Officials from the National Institutes of Health (NIH), in a hearing last Wednesday before a subcommittee of the US Congress, admitted that breast cancer research leaders had been slow to acknowledge that some patients had been inappropriately entered into a trial that established lumpectomy as effective treatment for early breast cancer (BMJ, 9 April). At the same time, however, the NIH officials urged Congress not to delay the tamoxifen trial.
NIH official Dr Leslie Ford told the Senate Cancer Coalition legislators that the NIH planned to restart the tamoxifen trial, which had been suspended along with other major studies run by the breast cancer study project at the University of Pittsburgh. At that time the tamoxifen trial was not seen as presenting problems, but federal auditors wanted to review all research conducted by the study group.
Now senators are concerned that tamoxifen may be too dangerous to test as a preventive agent, even though it has been established as an effective treatment for women already suffering from breast cancer.
The 270 centre study began in 1992 and the NIH hopes to enrol about 16 000 women who are considered to be at higher than average risk of getting breast cancer. So far 11 000 women have enrolled but Cynthia Pearson of the National Women's Health Network testified last week that no other preventive measure was as risky as tamoxifen. For example, she estimated that current data suggested that about 2% of women taking tamoxifen for five years (the study's planned length) suffer either deep venous thromboses or uterine cancer. Therefore, she said, among the 8000 women who receive tamoxifen about 100 would suffer “major illnesses” from the drug and “we can predict that 10 to 15 will die.” But Dr Ford of the NIH pointed to National Cancer Institute's estimates that tamoxifen could prevent up to 120 breast cancer cases in the same group. All participants agreed that women in the tamoxifen trial should receive complete information on the drug before consenting to enter it.
Unless Congress explicitly acts otherwise the NIH will go ahead to restart the prevention study. The senators also reviewed the sluggish process that resulted in the March public announcement that data from the lumpectomy study had been altered by a Canadian surgeon. Senator Connie Mack, a Republican from Florida, said that the University of Pittsburgh and the NIH had to work actively to reassure North Americans that such practices would be prevented, or at least found and disclosed much earlier.
When asked why they had not detected the study's problems earlier the Pittsburgh doctors had no answer. They said that such answers would have to come from the study group's leader, Dr Bernard Fisher, who has been dised as chief administrator. So far, Fisher has failed to appear before congressional investigators.