The UK was the first country in the EU to have a nationwide programme for breast screening using mammography. It developed from the Forrest Committee's recommendations and began in 1988. The aim of the programme is to reduce mortality from breast cancer in the population screened.

Women aged 50 -70 are invited for screening at three-yearly intervals. There is now clear evidence that two mammographic views significantly improve both sensitivity, particularly for small breast cancers, and specificity (14). Since 2003 two views of each breast are now taken. Research has suggested that this can increase the detection rate of breast cancers by 25% or more (15).

Women under 50 are not offered routine screening. One reason is because mammograms do not appear to be as effective in pre-menopausal women, possibly because the density of the breast tissue makes it more difficult to detect problems and also because the incidence of breast cancer is lower (16).

During the menopause, the glandular tissue in the breast "involutes" and the breast tissue is increasingly made up of only fat. This is clearer on the mammogram and makes interpretation of the x-ray more reliable. Breast cancer is also far more common in post-menopausal women and the risk continues to increase with rising age (16).

Although a small reduction in mortality is achievable in younger women (40-50) it is much less cost effective because of the lower incidence of breast cancer. In Europe the consensus view is that mammographic screening of younger women on a population basis cannot be justified (14).

Potential concerns about screening for breast cancer

Intervals of screening

The optimal frequency of breast cancer screening has been a subject of debate since its introduction in the UK. Results from a UKCCCR randomised trial were published in 2002 directly comparing different screening intervals.

The trial demonstrated there was a small and insignificant advantage to annual screening (14). Shortening the screening interval in this age group would only have a relatively small effect on breast cancer mortality. It was recommended therefore that improvements to the screening programme would be targeted more productively on areas other than the screening interval, such as improving the screening quality (17).

Radiation risk

It has been calculated that for every two million women aged over 50 who have been screened by means of a single mammogram, one extra cancer a year after 10 years may be caused by the radiation delivered to the breast. Compared with an incidence of breast cancer that approaches 2000 in every million women aged 60, this risk is very small (14).

The value of breast screening

Blanks et al in their research on the effects of the breast screening programme for England and Wales between 1990 and 1998 demonstrated that it is saving at least 300 lives per year (18). That figure is set to rise to 1250 by 2010 (19).

It is thought that by 2010 the effect of the screening programme, combined with improvements in treatment and other factors (including cohort effects), could result in halving the breast cancer death rate in women aged 55 - 69 from that seen in 1990.

The World Health Organisation's International Agency for Research on Cancer (IARC) concluded that mammography screening for breast cancer reduces mortality. The IARC working group, comprising 24 experts from 11 countries, evaluated all the available evidence on breast screening and determined that there is a 35 per cent reduction in mortality from breast cancer among screened women aged 50 – 69 years old. This means that out of every 500 women screened, one life will be saved (20).

Breast self examination and breast awareness as breast screening methods

More than 90% of breast cancers are found by women themselves (21). Breast awareness is advocated rather than a rigid adherence to monthly self-examination. A randomised trial of breast self examination in Shanghai was published in 2002. This showed that intensive instruction in BSE did not reduce mortality from breast cancer (22).

It is advised that women continue to be breast aware and report any unusual changes in their breasts to their general practitioner. This could lead to a reduced delay in the presentation of any symptoms discovered by women themselves (23).

Cancerbackup have information for women who have had or are about to have breast screening.

Women at increased risk due to family history

Women with one first-degree relative with breast cancer are at a slightly increased risk of developing cancer themselves. This risk is higher if other close relatives in the family have breast or ovarian cancer, and if these cancers develop at an early age.

Breast cancer genes

About 4–5% of breast cancer cases are due to high-penetrance susceptibility genes. Two of these genes, BRCA1 and BRCA2, have been identified and localised to chromosomes 17 and 13 respectively. A number of other high-penetrance genes are likely to be identified in the future. The contribution of other genes such as TP53, HRAS1, the ataxia-telangiectasia and HNPCC genes remains unclear.

In a few cancer genetics centres, gene testing for mutated BRCA1 or BRCA2 genes is offered to families with four or more relatives with breast or ovarian cancer in three generations.

Management of women at higher risk of breast cancer

Local breast units and regional cancer genetics centres provide information about screening for women at a higher risk due to family history. Trials are also looking at the role of screening for these women (24, 25).

There are several options available for women with a strong family history or identified genetic risk. These are outlined in the genetics section.

One option is regular breast screening (regular breast examinations, mammography and or MRI scanning). A recent study found that MRI screening was almost twice as effective as mammography in detecting breast cancer in women under the age of 50 with a very strong family history of breast cancer (26). However MRI screening for this purpose is not widely available on the NHS. NICE is currently reviewing its guidelines with regard to MRI screening of women in particular populations of women who are at high risk of developing breast cancer because of their family history.

Women who are found to have the BRCA 1 or 2 mutations or who are considered to be at high-risk of developing breast cancer due to their family history may consider bilateral mastectomy.

Cancerbackup has information about this risk reducing surgery.