Breast cancer screening error: fatal mistake or lucky escape?
BMJ 2018; 361 doi: https://doi.org/10.1136/bmj.k2036 (Published 08 May 2018) Cite this as: BMJ 2018;361:k2036
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Whether breast cancer screening error is to be assessed as a fatal mistake or lucky escape depends on the following facts of mammograms.
Mammograms are the best breast cancer screening tests we have at this time. But mammograms have their limits. Overall, screening mammograms do not find about 1 in 5 breast cancers. About half of the women getting annual mammograms over a 10-year period will have a false-positive finding. Mammograms might not be helpful for all women (1). The extent of the influence requires being looked into.
A recent article stated that women with false positive screening results were less likely to return for their next recommended screening than those with a true negative result (62.0% vs. 68.7%). Compared to women with normal screening results, the adjusted risk ratios of fail-to-rescreen for women with imaging-only follow-up, needle sampling, and open biopsy were 1.08 (95% CI: 1.05-1.12), 1.72 (95% CI: 1.44-2.07) and 2.29 (95% CI: 2.09-2.50) respectively. (2). If the woman missed her screening due to age cut off and had previous false positive result, it is less likely to influence her.
The value of a screening mammogram depends on a woman’s overall health. Finding breast cancer early may not help her live longer if she has other serious or life-threatening health problems, such as serious heart disease, or severe kidney, liver, or lung disease. The American Cancer Society breast cancer screening guidelines emphasize that women with serious health problems or short life expectancies should discuss with their doctors whether they should continue having mammograms. (1) The expected loss to a woman of 71-years-old who missed screening due to cut off issue may not have much to lose.
However, the 70-year or 71-year birthday cut off is quite arbitrary and for convenience of periodic screening. This does not matter much in light of limitations of mammography. PHE modelling calculations might not have taken into consideration the quality issues of mammography and the probable loss due to over diagnosis, psychologic stress and unnecessary treatment.
1. https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-de...
2. Can J Public Health. 2018 Jan 22;108(5-6):e539-e545. doi: 10.17269/cjph.108.6154.
Competing interests: No competing interests
I write as one of the signatories of the letter to the Times last Saturday.
I, for one, cannot believe that a woman can die for want of a mammogram, because of an estimate that for every breast cancer death avoided there could be a life lost as a result of the over-diagnosis and over-treatment of up to 30% of all cases detected at mammography screening. [1] The idea that any woman in the cohort of those who lost out on an invitation to screen could sue the NHS for damages is utterly absurd. Even if you take the generous figure from the Marmot review of a 20% relative risk reduction of cause specific mortality, this is nowhere near the balance of probability demanded by the courts in medico-legal cases. [2] I think Jeremy Hunt has been very badly advised by his in house "experts" and should seek guidance on how get out of this hole from those who keep up to date with the literature.
[1] Baum M, Harms from breast cancer screening outweigh benefits if death caused by treatment is included. Br Med J 2013, 346: f385.
[2] Marmot G, Altman DG, Cameron DA, Dewar JA, Thompson SG, Wilcox M. The Independent UK Panel on Breast Cancer Screening (2013) The benefits and harms of breast cancer screening: an independent review. Br J Cancer 108(11): 2205–2240.
Competing interests: No competing interests
"Invitation" for mammography: a wolf in sheep's clothing for "forced marketing"?
Hawkes must be commended for his brilliant systemic analysis of the mammography invitations which were not sent to older women and, for daring to call a spade a spade: the worst problem is that screening advocates failed to acknowledge that the already equivocal benefits of screening could even be non-existent in this population.(1)
Indeed, extending screening mammography in Australia to older women results in an even less favourable harm to benefit ratio than stopping at age 69.(2) Moreover, uptake should target those most at risk and there is room for improvement: uptake of screening (first and other, a prerequisite for effectiveness if any) by women aged 50-70 has decreased from 69% in 2005-6 to 60 in 2016-17.(4)
Last but not least, the term invitation deserves a semantic analysis. Invitation according to the Oxford Dictionary is «a situation or action that tempts someone to do something or makes a particular outcome likely.” Why should lay healthy people be invited to a test with a controversial harm/benefit ratio? Why does the "invitation" not provide adequate information? Pictographs with absolute numbers (using a consistent denominator), time frames and visuals employing the same scale for information on gains and losses of the options.(3) In such cases women are less likely to choose screening.(4) Seventeen and 27% of women in the UK overestimated the mortality reduction from mammography by an order of magnitude of 100 and 200 respectively; only 2% gave the right figure.(5)
1 Hawkes N. Breast cancer screening error: fatal mistake or lucky escape? BMJ 2018;361:k2036
2 Jacklyn G, Howard K, Irwig L, Houssami N, Hersch J, Barratt A. Impact of extending screening mammography to older women: Information to support informed choices. Int J Cancer 2017;141:1540-1550.
3 NHS Digital. Breast screening programme. 4 April 2018. Available at https://files.digital.nhs.uk/pdf/m/f/breast_screening_programme__england... Accessed 27 June 2018.
4 Zikmund-Fisher BJ, Fagerlin A, Ubel PA. A demonstration of “less can be more” in risk graphics. Med Decis Making. 2010;30:661-671.
5 Hersch J, Barratt A, Jansen J, et al. Use of a decision aid including information on overdetection to support informed choice about breast cancer screening: a randomised controlled trial. Lancet 2015;385:1642–52.
6 Gigerenzer G, Mata J, Frank R. Public knowledge of benefits of breast and prostate cancer screening in Europe. J Natl Cancer Inst 2009;101:1216-20.
Competing interests: No competing interests