Intended for healthcare professionals

CCBYNC Open access
Research

Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study

BMJ 2017; 359 doi: https://doi.org/10.1136/bmj.j5224 (Published 05 December 2017) Cite this as: BMJ 2017;359:j5224

Re: Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study

How can anyone attempt to evaluate the impact of mammography screening and breast cancer treatment without knowing which women were screened and which were not, or which patient got what type of treatment?

Philippe Autier and colleagues claim that “The Dutch mammography screening programme seems to have little impact on the burden of advanced breast cancers, which suggests a marginal effect on breast cancer mortality”1. These authors belong to a small group who repeatedly claim that modern mammography screening has little or no effect in decreasing the advanced cancer rate or reducing breast cancer death. However, they cannot substantiate their conclusions because they have no data about each tumor’s detection mode, so they cannot distinguish among cancers detected in women who attended screening (screen detected plus interval cases) and cancers that were detected outside screening. In addition, Autier and colleagues’ article has a severe contamination from breast cancer deaths that occurred within the screening period, but were diagnosed before screening started. One cannot expect mammography screening to have an impact upon women whose cancers were detected screening began. During the first ten years of screening more than 50% of breast cancer deaths occur among women whose cancers were diagnosed before screening started2,3. These serious limitations make it impossible to perform a reliable scientific study. The real tragedy here is that the peer review process of so many journals is unable or unwilling to appreciate these basic flaws.

How many more articles will be published without access to accurate data on detection mode and without sufficiently long follow-up? This type of research has been a recurring theme during the past decade, harming women and confusing their physicians. This article should not have been published in a peer-reviewed journal.

In stark contrast to the conclusions by Autier and colleagues, the Health Council of The Netherlands concluded in their report4 that “In the population based screening programme in the Netherlands, 1,200 women must undergo mammography to prevent one breast cancer death. When screening prevents the death of a woman from breast cancer, she is spared the terminal phase of the disease and on average gains 16.5 life-years. A cost-effectiveness analysis indicates that the cost per life-year gained is 1,600 euros. The existing population screening programme prevents an average of 775 breast cancer deaths per year. That is two to three times the estimated number of women affected by overdiagnosis. The Committee concludes that, because of screening, fewer women die from breast cancer. The decrease in mortality relevantly outweighs the harms”.

References
1. Philippe Autier, Magali Boniol, Alice Koechlin, Cécile Pizot, Mathieu Boniol. Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study. BMJ 2017;359:j5224 http://dx.doi.org/10.1136/bmj.j5224
2. Stephen W. Duffy, L. Tabar, Hsiu-Hsi Chen et al. The Impact of Organized Mammography Service Screening on Breast Carcinoma Mortality in Seven Swedish Counties. A Collaborative Evaluation. Cancer 2002;95:458–69. © 2002 American Cancer Society. DOI 10.1002/cncr.10765.
3. Nyström L, S Törnberg. Cochrane Center produces flawed research. BMJ 6 April 2010. BMJ 2010;340:c1241.
4. Health Council of the Netherlands. Population screening for breast cancer:
expectations and developments. I-1272-12/LvR/pm/894-A65.

Competing interests: No competing interests

07 December 2017
Laszlo K Tabar
radiologist
Peter B Dean
Department of Mammography, Falun Central Hospital, Sweden
Lasarettsvagen 10, 79182 Falun, Sweden.