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Racial Differences in Breast Cancer Mortality
We read with interest the article by Chu et al.1 We agree with Chu et al that "the increasing disparity between breast cancer mortality rates in black and white women is disturbing."1(p527) In fact, in our recent article,2 we called for studies to "help identify reasons for the epidemic of breast cancer deaths in black women." However, we believe there are a few key points neglected by Chu et al that are worthy of emphasis.
First, Chu et al state that the widening black/white breast cancer mortality disparity comes in the face of declining mortality rates for white patients and stable rates for black patients. However, as shown in their article, mortality rates in black patients actually increased throughout the 1980s and into 1995. We have shown that mortality rates from breast cancer in black women have been increasing since at least 1950, while rates in white women have remained stable from 1950 through 1990. In fact, in 1950, age-adjusted breast cancer mortality rates for black women were 22% lower than for white women; by 1971, the rates were similar for black and white women; and by 1992, the rates for black women were more than 15% higher than for white women.
Second, Chu et al conclude that "medical interventions are responsible for much of the decreasing mortality in white women."1(p528) While this is an intriguing hypothesis, it remains to be supported by data. It is important to note that overall, most of the decrease in mortality in white women has occurred only since 1990. In addition, there has not been a notable decline in mortality rates for white women older than 70 years. We are unaware of any recently introduced medical interventions that could explain this finding. The widespread use of treatments such as lumpectomy and adjuvant therapy (ie, tamoxifen) were introduced long before the recent decline in breast cancer mortality observed in a subset of white women.
Finally, we do not agree with the authors' conclusion that racial differences in the response to treatment are unlikely to account for racial differences in breast cancer mortality. A recent publication by Gail et al3 indicates that black women would be expected to have more adverse outcomes with prophylactic tamoxifen use than white women. Thus, it is possible that black women have a poorer response to adjuvant tamoxifen use than white women. Future studies are urgently needed to identify racial differences in the response to treatments, including tamoxifen and other therapies, as well as to identify reasons for the dramatic increase in breast cancer mortality in black women observed during the last 50 years.
Jodi A. Flaws, PhD;
Trudy L. Bush, PhD
Department of Epidemiology and Preventive Medicine
University of Maryland School of Medicine
660 W Redwood St
Baltimore, MD 21201
(e-mail: jflaws{at}som.umaryland.edu)
Craig J. Newschaffer, PhD
Johns Hopkins School of Hygiene and Public Health
Baltimore
1. Chu KC, Tarone RE, Brawley OW. Breast cancer trends of black women compared with white women. Arch Fam Med. 1999;8:521-528.
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2. Flaw JA, Newchaffer CJ, Bush TL. Breast cancer mortality in black and white women: a historical perspective by menopausal status. J Womens Health. 1998;7:1007-1015.
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3. Gail MH, Costantino JP, Bryant J, et al. Weighing the risks and benefits of tamoxifen treatment for preventing breast cancer. J Natl Cancer Inst. 1999;91:1829-1846.
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In reply
The clearly stated objective of our study was to investigate the different breast cancer trends in black and white women during the 1990s.1 Figure 1 of our article demonstrated the differences in longer-term trends noted by Flaws et al. These long-term differences between the black and white mortality trends have been examined and quantified in earlier publications.2-3
Evidence supporting the conclusion that the recent calendar period decrease in breast cancer mortality rates in white women is because of medical intervention has been presented earlier.2, 4-5 Similar conclusions were reached by other researchers, who examined declining breast cancer mortality rates in the 1990s in England and Wales.6-7
As noted by Flaws et al, the difference in the projected benefit between black and white women from tamoxifen therapy is because of the increased risk among black women of certain comorbid diseases, not because of a differential response of breast cancer to tamoxifen therapy.8 Deaths from such comorbid diseases would not affect the breast cancer mortality rates analyzed in our article, unless it was known that the diseases were caused by cancer treatment. A recent study, like several others referred to in our article, found that the survival of black breast cancer patients given appropriate treatment was similar to that of comparable white breast cancer patients.9
Finally, we agree with Flaws et al that further studies of the divergent breast cancer trends in black and white women should be a high priority.
Kenneth C. Chu, PhD;
Robert E. Tarone, PhD;
Otis W. Brawley, MD
Office of Special Populations Research
National Cancer Institute
900 Rockville Pike, Building EPS, Room 320
Bethesda, MD 20892
(e-mail: kc10d{at}nih.gov)
1. Chu KC, Tarone RE, Brawley OW. Breast cancer trends for black women compared with white women. Arch Fam Med. 1999;8:521-528.
2. Tarone RE, Chu KC, Gaudette LA. Birth cohort and calendar period trends in breast cancer mortality in the United States and Canada. J Natl Cancer Inst. 1997;89:251-256.
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3. Chu KC, Baker SG, Tarone RE. A method for identifying abrupt changes in US cancer mortality trends. Cancer. 1999;86:157-169.
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4. Chu KC, Tarone RE, Kessler LG, et al. Recent trends in US breast cancer incidence, survival and mortality rates. J Natl Cancer Inst. 1996;88:1571-1579.
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5. Tarone RE, Chu KC. Response to Feigelson HS, Henderson BE, Pyke MC. Re: Recent trends in U.S. breast cancer incidence, survival, and mortality rates [letter]. J Natl Cancer Inst. 1997;89:1811-1812.
6. Beral V, Hermon C, Reeves G, Peto R. Sudden fall in breast cancer death rates in England and Wales [letter]. Lancet. 1995;345:1642-1643.
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7. Quinn M, Allen E. Changes in incidence of and mortality from breast cancer in England and Wales since introduction of screening. BMJ. 1995;311:1391-1395.
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8. Gail MH, Constantino JP, Bryant J, et al. Weighing the risks and benefits of tamoxifen treatment for preventing breast cancer. J Natl Cancer Inst. 1999;91:1829-1846.
9. Dignam JJ. Differences in breast cancer prognosis among African-American and Caucasian women. CA Cancer J Clin. 2000;50:50-64.
ABSTRACT
Arch Fam Med. 2000;9:412-413.
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