[Breast cancer screening]

Breast cancer screening is the subject of a vigorous debate. This concerns both the estimation of the benefit derived from mammographic screening, i.e. the breast cancer mortality reduction associated with screening, and the estimation of overdiagnosis, which is the detection of a breast cancer that would never have become symptomatic during the lifetime of the woman. The overview of all trials gives an estimation of 20 % for the breast cancer mortality reduction in the population invited to screening and of 30 % in the population effectively screened. Estimating overdiagnosis is more difficult and many estimations are biased for want of a proper adjustment to correct for systematic differences between the compared populations. None of the correctly adjusted estimations are above 10 %. Breast cancer screening is more beneficial than detrimental, but the benefit is not large. A woman who refuses breast cancer screening is less unreasonable than a woman who continues to smoke since tobacco kills half of regular smokers.