Bonnie Krull, 54, had already had enough breast-caner scares for one lifetime, with a few to spare for reincarnations (再生). Her great-aunt, aunt, mother and sister all developed the disease. A few years ago Krull herself, a telecom manager in Los Angeles and a mother of two grown sons, was being prepped for surgery for what her doctor concluded was a malignancy (恶性肿瘤) in her left breast. As she underwent a final mammogram so the surgeon could pinpoint where to cut, and with the Ⅳ already dripping, the radiologist suddenly muttered that the lump had vanished. Heartened for the clinical trial of tamoxifen, a drug that preliminary data suggested might prevent breast cancer. Last week federal health officials announced at a press conference results that convinced Krull, who by chance was in the group receiving tamoxifen rather than a placebo, that her luck was holding. Among the 13,388 high-risk women in the trial, tamoxifen reduced the incidence of breast cancer a full 45 percent. "I really believe that tamoxifen saved me," says Krull, "and that I am going to be the one who breaks the link in the family chain of cancer."
Normally circumspect scientists were no less euphoric (愉快的). "For the first time we have demonstrated that one can alter the incidence of breast cancer," says Dr. Norman Wolmark, chairman of the National Surgical Adjuvant Breast and Bowel Project at Allegheny University of the Health Sciences, which ran the tamoxifen trial, and not just by tinkering at the margins. The 45 percent lower incidence Of invasive breast cancer among women receiving tamoxifen--85 cases compared to 154--was so stark that, in a controversial decision, the researchers ended the study 14 months ahead of schedule.
The results were not all positive, though. The women on tamoxifen, who took two 10-milligram pills each day, also had 33 cases of endometrial cancer versus 14 in the placebo group, 17 cases of pulmonary embolism (potentially fatal blood clots in the lung) compared with six among the women on a placebo and 30 cases of dangerous lung clots in major veins compared with 19 in the placebo group. Tamoxifen, clearly, is not the silver bullet that will kill breast cancer. "This is not primarily about tamoxifen," says oneologist Nikolay Dimitrov of Michigan State University. "This is a proof of the concept that prevention works. Now we can look for new chemopreventives without the side effects of tamoxifen." Other such drugs are in the pipeline. Researchers hope to begin a clinical trial on one, raloxifene, as early as this fall. Made by Eli Lilly and Co., raloxifene serendipitously turned out to lower the incidence of breast cancer among women on whom it was being tested against osteoporosis.
Until the perfect preventive comes along, should women at high risk for breast cancer ask their doctors for tamoxifen? (Because tamoxifen has been used for more than 20 years as a breast cancer treatment, doctors can prescribe it for such "off-label" uses as prevention, but government approval of such a use is at least six months away.) Many worried women are considering it. Karen Recht, a gift-shop manager in Wheeling, W. Va. , was in the tamoxifen trial. As chance would have it, she received the placebo. Recht, 57, volunteered because she wanted to help "the two little girls my sister (who died of breast caner at 45) left behind. I never dreamed I would benefit. But now I'm very tempted to try tamoxifen. I feel like it will give me five more years in which I won't get breast cancer."
The results announced last week apply just to high-risk women, the only kind participating in the study. For women at low risk for breast cancer, there is no evidence that the benefits of tamoxifen outweigh the dangers. "High risk" was defined as having the same chance of getting breast cancer as a 60-year-old American woman: a 1.7 percent chance of getting the disease within
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