DOI: 10.12809/hkmj187405
© Hong Kong Academy of Medicine. CC BY-NC-ND 4.0
Breast screening controversy and the ‘mammography wars’—two sides to every story
Ashley Kieran Clift, BA, MB, BS
Department of Surgery and Cancer, Imperial College London, United Kingdom
Corresponding author: Dr Ashley Kieran Clift (
 Full paper in PDF
To the Editor—Whilst the emphasis on shared decision making in breast screening of Sitt et al1 is warmly welcomed, one struggles to visualise how this can be promoted when their overview could arguably be condensed into three major take-home messages: (1) any study critical of screening is ‘controversial’; (2) risks of screening are overstated; and (3) harms of not screening are overestimated.
The “mammography wars” are predicated by the multiple ways one may analyse mammography screening studies. Estimates of the harms versus benefit “balance sheet” vary wildly depending on the approach utilised (Table).2 3 Furthermore, estimates of overdiagnosis rates can range from 0% to 54%,4 dependent on whether studies are based on modelling or cohort observation, which denominator is used, and what adjustments are made (themselves sometimes debated). Essentially, the body of evidence can be “tortured” to give almost any answer you desire. Surely no other topic in medicine can show so many ways to slice the same cake?

Table. Collection of recent studies of varying methodologies and resulting estimation of benefits and harms of breast screening
The most ardent supporter and passionate dissident can agree that breast screening is imperfect—arguably favourable to suppressing any component of the debate is providing a balanced view. This does not need to constitute a conciliatory back-of-the-envelope calculation—this ‘third way’ could manifest as the (importantly) independent United Kingdom panel report5 which calculated that screening 233 women for 20 years can prevent one death, but three women will be overdiagnosed and overtreated.
Only when Hong Kongers are fully informed of the potential benefits and harms can they make truly informed choices.
The author has no conflicts of interest to declare. The author had full access to the data, contributed to the study, approved the final version for publication, and takes responsibility for its accuracy and integrity.
1. Sitt JC, Lui CY, Sinn LH, Fong JC. Understanding breast cancer screening—past, present, and future. Hong Kong Med J 2018;24:166-74. Crossref
2. Gøtzsche PC, Jørgensen KJ. Screening for breast cancer with mammography. Cochrane Database Syst Rev 2013;(6):CD001877. Crossref
3. Paci E, Broeders M, Hofvind S, Puliti D, Duffy SW, EUROSCREEN Working Group. European breast cancer service screening outcomes: a first balance sheet of the benefits and harms. Cancer Epidemiol Biomarkers Prev 2014;23:1159-63. Crossref
4. Løberg M, Lousdal ML, Bretthauer M, Kalager M. Benefits and harms of mammography screening. Breast Cancer Res 2015;17:63. Crossref
5. Independent UK Panel on Breast Cancer Screening. The benefits and harms of breast cancer screening: an independent review. Lancet 2012;380:1778-86. Crossref