Screening for breast cancer with mammography

This is the title of a Cochrane review I first published in 2001 and lastly updated in 2013 (1). Because many more deaths have now been published (2,3), I updated the review again on 10 January 2023, and on 6 February, my co-author had independently assessed the new data and agreed with what I had found.

The updated mortality data show even more clearly than before that mammography screening does not save lives, which is the official mantra used for justifying screening. When we analysed invitations to breast screening from seven countries, we found that 19 pamphlets (95%) had suggestive headlines, such as, “Have a screening mammogram, it may save your life.”

Cochrane has become a highly bureaucratic and ineffective organisation, which is why its major funder stripped all the funding to the UK based Cochrane groups from 31 March 2023. It will likely take many months before our updated Cochrane review gets published. I do not find it fair to withhold any longer the information we collected about mortality to women contemplating if they should attend screening. I therefore summarise what we found here.

Two of the three studies with adequate randomisation have been updated with many more deaths. Breast cancer mortality is an unreliable outcome that is biased in favour of screening, mainly because of differential misclassification of cause of death. We therefore need to look at total cancer mortality and total mortality instead.

The trials with adequate randomisation did not find an effect of screening on total cancer mortality, including breast cancer (risk ratio 1.00, 95% confidence interval 0.96 to 1.04). All-cause mortality was not significantly reduced either (risk ratio 1.01, 95% CI 0.99 to 1.04).

As reported earlier, total numbers of lumpectomies and mastectomies were significantly larger in the screened groups (risk ratio 1.31, 95% CI 1.22 to 1.42), as were number of mastectomies (risk ratio 1.20, 95% CI 1.08 to 1.32).

These results – and indeed, many others – can only lead to one logical conclusion: Mammography screening is harmful and should be abandoned, as I have explained earlier.

1 Gøtzsche PC, Jørgensen KJ. Screening for breast cancer with mammography. Cochrane Database Sys Rev 2013;6:CD001877.

2 Miller AB, Wall C, Baines CJ, Sun P, To T, Narod SA. Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial. BMJ 2014;348:g366.

3 Duffy SW, Vulkan D, Cuckle H, Parmar D, Sheikh S, Smith RA, et al. Effect of mammographic screening from age 40 years on breast cancer mortality (UK Age trial): final results of a randomised, controlled trial. Lancet Oncol 2020;21:1165-72.