The number of women who would need to be screened regularly by mammography to prevent one death from breast cancer

Abstract

The number of women who would need to be screened regularly by mammography to prevent one death from breast cancer depends strongly on several factors, including the age at which regular screening starts, the period over which it continues, and the duration of follow-up after screening. Furthermore, more women would need to be INVITED for screening than would need to be SCREENED to prevent one death, since not all women invited attend for screening or are screened regularly. Failure to consider these important factors accounts for many of the major discrepancies between different published estimates. The randomised evidence indicates that, in high income countries, around one breast cancer death would be prevented in the long term for every 400 women aged 50–70 years regularly screened over a ten-year period.

Summary of the Evidence of Breast Cancer Service Screening Outcomes in Europe and First Estimate of the Benefit and Harm Balance Sheet

“…It is important to note that quoted benefits and harms are dependent on the intervention delivered, the data sources used and the denominator referred to. For example, our estimated numbers of lives saved exceed those estimated by Beral et al 41 because ours is based on 20 years of screening and on the service screening results in Europe. Those of Beral et al 41 pertained to 10 years of screening and the randomized trial results.…”

Why the time is right to tackle breast and cervical cancer in low-resource settings

“…29 The highest impact on mortality, though, will come from earlier detection, accurate diagnosis and more widely available basic treatment. Although screening mammography has been shown to reduce breast cancer mortality in high-income countries, 30 it is generally neither affordable nor appropriate for detecting tumours in the advanced stages usually seen in low-resource settings, where women often present with tumours that are easily palpable, visible or ulcerated through the skin. 31 Interventions that promote clinical breast examination and increase community awareness of the symptoms of breast cancer and of the importance of screening can greatly increase the fraction of tumours that are detected at an earlier stage, before they become readily palpable or visible, as shown by Mittra et al and Sankaranarayanan et al 32,33 The role of screening mammography is still being debated.…”

A Monte Carlo analysis of breast screening randomized trials

“…Other studies [6][7][8][9], based on a more restricted number of trials and for women with different age ranges, quoted absolute risk reductions ranging between 0.075% and 0.88%. These small values constitute one of the main difficulties to justify breast cancer screening programmes because other possible issues, such as differences in the incidence and prevalence between different populations, changes in the breast cancer incidence over time, differences in the screening programme configurations, and insufficient follow-up times, may strongly influence them or even overrule their external validity.…”