Screening for breast cancer with mammography: updated review

I first published this Cochrane review in 2001 and lastly updated it in 2013. Because many more deaths have now been published, I updated the review again in January 2023, and a month later, 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, and I therefore published them in May 2023 on my website in the public interest.

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).

Screening has been sold to the public with the claims that it saves lives and saves breasts. It does neither and increases mastectomies. 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.

Cochrane has become a highly bureaucratic and ineffective organisation. We therefore don’t know when our updated review will be published in the Cochrane Library. When I first published it, in 2001, the Cochrane Breast Cancer Group would not allow us to publish the harms of screening even though they were included in the protocol for the review, the group had approved and published. Back then, we needed to publish our review in The Lancet to ensure the harms became known. It took five years, with complaints to the Cochrane Steering Group, before the harms data also became included in the Cochrane review.

We responded to the peer review comments on our updated review in March 2024, but when we asked in June, the Cochrane editors were unable to tell us when we would hear back from them, and holidays are approaching.

For this reason, we have decided to upload our submitted review on a preprint server. We believe this is helpful for women contemplating if they should attend mammography screening and for authorities who are currently reconsidering their guidelines.