This certainly sounded like wonderful news. The death rate among white women declined a total of about six percent. This was the largest short-term decline in the breast cancer death rate since 1950. However, deaths among African-American women actually increased 2.6 percent in the same time.
The downward slope was seen in all age groups, but was accentuated in the younger age groups of whites:
For ages 70-79 there was a 3.4 percent decrease.
The American Cancer Society (ACS) immediately jumped on these statistics as a triumph for mammography and aggressive adjuvant treatment.
"This is very encouraging news," said Dr. Robert A. Smith of the ACS. "We invested in research and it looks like it has paid off. And with some other drugs coming on line, and screening continuing to increase, it is possible that the trend will continue" (N.Y. Times, 1/13/95).
Government spokespersons were far more circumspect in interpreting the data. HHS Secretary Donna Shalala said, "While there remain many reasons for concern, these findings overall are encouraging....We do not have a thorough understanding of the causes, and we are still very far from seeing a positive trend for all American women" (HHS News, 1/11/95).
Even Dr. Broder admitted, "Much research will be necessary to understand the specific reasons for the decline." He believes that "for the very youngest women...advances in adjuvant chemotherapy almost assuredly are playing a major role."
Breast cancer death rates can vary for many reasons other than more aggressive treatment. As even the Times (1/13) pointed out, "changes in risk factors like diet, fertility and oral contraceptive use" can be "important factors in the decline." Who is to say that some major shift in diet among American women--perhaps an increased emphasis on fruits and vegetables--has not been the main factor that has led to this decline? For young women, mortality rates had already begun to decline before the widespread introduction of adjuvant treatments. Between 1955‚1985, their breast cancer mortality rates declined 15‚20 percent (Ursin, et al. Trends in Cancer Incidence and Mortality, I.C.R.F., 1994).
Unexplainable changes in mortality rates sometimes occur. For example, the rates for various age groups in Norway, Hungary and Singapore all declined at times between 1965 and 1985. One must be cautious in interpreting such statistics, for fear of suggesting inappropriate treatments based on what may be statistical flukes.
In response to our questions about the latest statistics, John C. Bailar III, M.D., Ph.D., chair of the Department of Epidemiology and Biostatistics at McGill University told the Chronicles:
"I am simply not able to make an informed judgement at this time about whether the reported decline is real, or possibly, a statistical artifact. One of the things that I want to look at is the figures year-by-year, to see whether the reported change occurred gradually over a period of several years, or is concentrated in the most recent year. If the latter, I think the chances of a statistical problem in the data are very high.
"I also want to give more thought to the observation that it was of approximate equal size in the age groups 40-49 and 50-59, because breast cancer in these two age ranges so often acts like different diseases. The similarity in reported rates again suggest to me that there may be a problem in the data, rather than a real change.
"A further point for consideration is whether deaths are being delayed rather than prevented. A substantial delay may of course be very valuable to the patient, the family, and society, and we would all welcome that much in the way of progress. If that is what is happening, however, we should not confuse it with the greater benefits of a real long-term reduction in mortality."
Bailar added, "It is of course possible that the change is real, and that would be a most welcome observation. "Breast cancer is a terrible disease, and I would be at least as glad as anyone else to see its frequency reduced"
"In short," he concluded, "I have some questions about the data that
I cannot at present answer. I do expect to continue watching this situation,
and I hope that the picture is more clear within the next few months."
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