Screening for breast cancer

Methods of screening

There is no evidence that clinical examination, breast ultrasonography, or teaching self examination of the breast are effective tools for early detection. However, randomised controlled trials have shown that screening by mammography can significantly reduce mortality from breast cancer by up to 40% in those who attend. The benefit is greatest in women aged 50-70 years. Published data from the combined Swedish trials showed an overall reduction in breast cancer mortality of 29% during 12 years of follow up in women aged over 50 who were invited for screening.

Screening tests should be simple to apply, cheap, easy to perform, and easy and unambiguous to interpret and should identify those with disease and exclude those without. Film screen mammography requires high technology equipment, special film and dedicated processing, highly trained radiographers to perform the examinations, and highly trained readers to interpret the films. Mammography is at present the best screening tool available and was the first screening method for any malignancy which has been shown to be of value in randomised trials. The potential benefits of digital mammography remain to be evaluated.

Organisational aspects of screening

Over 70% of the target population must accept the invitation to participate if screening is to reduce mortality significantly, and the cost per life year saved rises if fewer participate. To achieve optimal participation accurate lists of names, ages, and current addresses are required. Factors affecting attendance for screening include the …