Breast Cancer Screening

One million women each year will develop breast cancer worldwide and since 1963 many trials have looked at whether screening will affect the outcome in terms of mortality and morbidity. Several countries have now set up screening programmes to call women for routine screening.

The breast cancer screening programme in the UK has been set up to allow for the early detection and treatment of breast cancer in women. The programme was initiated in 1990 following the Forrest report,¹ and has 80 units across the UK each responsible for the screening of approximately 45,000 women.²
The budget for the screening is around ?75 million.

All women between the ages of 50 and 70 are invited to attend for screening every three years. It is a rolling programme, which means that not all women will be invited when they reach 50 years, but all will be invited before their 53rd birthday.
Women over the target age may request mammography through their GP.

Screening in the UK is a nationally co-ordinated programme, with national standards monitored through a quality assurance network.
Screening takes place in the form of mammography, or x-ray of the breast, which allows small tumours to be detected before they are palpable. Since 2003, two images of each breast have been taken, craniocaudial, and mediolateral, and this increases the detection rate of even smaller abnormalities by up to 43%.²

The reduction in mortality for women taking part in screening between the ages of 50 and 69 is thought to be of the order of 35%.
A Finnish study showed 47% reduction in mortality in the 65-69 year old cohort.³ The overall reduction in mortality for 55-69 yearolds was 37%.
For women aged 40-49 there is only limited evidence of a reduction in mortality. This may be due to the difficulties in interpreting mammograms in pre-menopausal women, due to glandular breast tissue, and also to the lower incidence of breast cancer in this age group.

Research has shown that the screening programme in the UK has resulted in the saving of approximately 300 lives per year since it began.
When the changes to screening were proposed in 2003, it was estimated that this would rise to 1250 per year by 2010.⁴ A recent report however has shown that the figure has already risen to 1,400 lives per year.⁵
Recent studies have also suggested that cancerous tumours detected by routine screening have a better outcome as measured by 10 year survival rate, than those tumours detected by other means.⁶

However, a Cochrane review on the subject of breast screening has concluded that the currently available reliable evidence does not show a survival benefit of mass screening and that the evidence is inconclusive in terms of breast cancer mortality.⁷

74.9% of women aged 53-64 had been screened at least once in the last three years
1.4 million women of all ages were screened within the programme.²
11,200 cases of cancer were diagnosed in women of all ages screened.⁵

Randomised controlled trials have shown that although screening confers significant reduction in breast cancer mortality, it has also been accompanied by an increase in breast cancer incidence, particularly during the early years of a screening programme. This has led to concerns about overdiagnosis. The current evidence is showing a minor (1%) increase in incidence,⁸ if any at all.⁹ Further, large scale evidence is required.
Although the benefits of screening may be considerable, it can be a very anxious time for many women. Research suggests however, that women are able to balance the anxiety against the effectiveness.¹⁰