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Modern mammography screening and breast cancer mortality: population study

BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g3701 (Published 17 June 2014) Cite this as: BMJ 2014;348:g3701

Re: Modern mammography screening and breast cancer mortality: population study

When the British Medical Journal publishes a paper challenging the benefits of mammography it commissions an editorial that supports the negative findings, yet when it publishes a paper that shows the benefits of mammography screening, editorial writers are commissioned to denigrate those results. The paper by Weedon-Fekjær reinforces the fact that even in the modern therapy era, mammography screening reduces deaths by 28% for women invited to be screened and 37% for those who actually attended screening (1). In their accompanying editorial Elmore and Harris find the "glass half empty" (2).

What is perhaps more disturbing is that a paper that trivialized the benefit of screening in Norway (reference 8) was published in the New England Journal of Medicine in 2010 claiming that mammography contributed little benefit for Norwegian women and making front page news in the U.S. Weedon-Fekhjaer et al diplomatically explain their contradictory results. In fact, the NEJM paper should have never passed peer review. A number of us were critical of the publication since it did not utilize direct patient data, and had only 2.2 years of follow-up (screening benefit begins to appear 5-7 years after it begins). Furthermore, the authors of the NEJM paper claimed that there had been very little screening in Norway prior to the National program. In fact, more than 40% of women were being screened in Norway prior to the National program (3). Subsequently, a paper showing a 43% decline in breast cancer deaths as a result of screening in Norway (4) got no media attention.

This is an increasingly disturbing trend where methodologically poor papers get published and create false impressions. When more scientifically derived analyses follow, and refute the negative conclusions, they are ignored.

Elmore and Harris denigrate screening claiming that much of the decline in deaths is due to improvements in therapy. Although trial data suggest improvements, there are actually no direct population data to support this contention. This latest paper, as has been seen with other studies, actually shows that most of the decline in deaths is due to screening. Therapy saves lives when cancers are treated earlier.

Males have access to the same therapies, yet while the death rate for women began a steady decline in 1990 in the U.S. after screening began in the mid 1980's, the death rate for men increased and then returned to the 1990 level while the death rate continued to decline for women. Men are not screened for breast cancer.

Peer review at some of the major medical journals has failed and has been superseded by publications based on journal biases. This is a dangerous situation. The media pass on the misinformation, and the medical community and the public are misled.

No one believes that mammography is the ultimate answer to breast cancer, but thousands of lives are being saved each year. This paper simply reinforces the scientific proof that early detection saves lives. While we await a cure (and none is on the horizon), early detection is the best method we have for saving lives. Journals need to recognize their ethical responsibility to provide unbiased information.

References

1.Weedon-Fekjær H, Romundstad PR, Vatten LJ. Modern mammography screening and breast cancer mortality: population study. BMJ 2014;348:g3701 doi: 10.1136/bmj.g3701

2.Elmore JG, Harris RP. The harms and benefits of modern screening mammography: Women need more balanced information. BMJ 2014;348:g3824 doi: 10.1136/bmj.g3824

3. Lynge E, Braaten T, Njor SH, Olsen AH, Kumle M, Waaseth M, Lund E. Mammography
activity in Norway 1983 to 2008. Acta Oncol. 2011 Oct;50(7):1062-7.

4. Hofvind S, Ursin G, Tretli S, Sebuødegård S, Møller B. Breast cancer mortality in participants of the Norwegian Breast Cancer Screening Program. Cancer. 2013 Sep 1;119(17):3106-12

Competing interests: No competing interests

18 June 2014
Daniel B. Kopans
Professor of Radiology
Harvard Medical School and Massachusetts General Hospital
Fruit Street, Boston, Massachusetts