Breast cancer screening is a well-established element of health services in the developed world. Based on the premise that serial mammography can detect tumours at an earlier stage, rendering them more amenable to treatment, women in their 50s and 60s are enrolled in national screening programmes. BreastCheck – the National Breast Screening Programme has been providing free mammograms to women aged 50-64 every two years, since 2000 – to date over 1.2 million mammograms to over 450,000 women, detecting more than 7,900 cancers.
In order for screening to be successful at a population level it must have a minimum uptake of 70 per cent. However the latest reported figures for BreastCheck show that in 2013, for the first time, this target was not reached. The reasons for this are unclear but may include the publication of a number of studies questioning the effectiveness of screening. The possibility of overdiagnosis and the effect of false positive results on the psychological health of women have also been highlighted.
The recent publication of a major international review of the latest evidence on breast cancer screening will be welcomed by its proponents and may help to reverse the decline in uptake among Irish women.The review, commissioned by the International Agency for Research in Cancer (IARC), the World Health Organisation's specialised cancer agency, concluded women aged 50-69 years who attend mammography screening reduce their risk of dying from breast cancer by 40 per cent compared to women who are not screened.
This relative risk translates to around eight deaths prevented per 1,000 women regularly attending screening. While IARC researchers acknowledged there were some harms associated with the early detection of breast cancer using mammography screening, it concluded the significant reduction in mortality observed in the 50-69 year age group outweighs the impact of adverse effects. This conclusion suggests the Government must also speed up the planned extension of BreastCheck to include women aged 65 to 69.