Mammography has not reduced breast cancer death, according to study

Although many medical doctors are quick to tell young women patients that they should have an annual mammogram -- a procedure that can cost $100 or more -- those tests may be useless.

That was the conclusion after the long-term Canadian National Breast Cancer Screening Study, which found that 40 to 49 year-old women who had annual mammographies for five years had no fewer breast cancer deaths than a group of women who did not have the screening.

The study appeared in the September 3, 2002, issue of Annals of Internal Medicine. The Canadian study, a large, randomized, controlled trial, has followed 50,430 women who were between ages 40 and 49 when initially enrolled between 1980 and 1985. The women in the treatment group received annual mammography along with breast physical examination and instruction on breast self-examination.

By the end of 1996, 105 women in the mammography screening group and 108 in the usual-care group had died from breast cancer. A total of 592 cases of invasive breast cancer and 71 cases of in situ breast cancer were diagnosed in the mammography group, compared with 552 and 29 cases, respectively, in the usual-care group.

The earlier seven- and 10-year results of the Canadian study also showed no reduction in breast cancer mortality after breast cancer screening with mammography, but some scientists withheld judgment, feeling that a longer follow-up period might reveal benefits. Thus, the results of this third status report had been eagerly awaited.

In a editorial published in the same issue, Steven Goodman, M.D., pointed to the fact that a number of studies have reached conflicting conclusions, triggering intense debate and argument. Despite some differences in research protocols and results, Goodman said the bottom line is clear. "Even under the most optimistic assumptions, mammography still cannot prevent the vast majority of breast cancer deaths," he emphasized.