Risks of breast cancer screening in over 70s
15th September 2014 – Including women over 70 in a national breast cancer screening programme does not lead to a large fall in advanced cases, and may actually lead to overdiagnosis and overtreatment, a Dutch study has concluded.
At present the NHS Breast Screening Programme offers screening to all women aged between 50 and 70 who are registered with a GP. They are sent an invitation to go for screening every 3 years.
In the Netherlands the upper age limit for screening was extended from 69 to 75 in 1998, which allowed researchers from the Leiden University Medical Centre to assess the impact on diagnoses of late-stage cancers in this upper age group.
They tracked 25,414 new cases of invasive and non-invasive breast cancer diagnosed among Dutch women in this age group from 1995 up to 2011.
Detecting more early cases
Analysis of the data showed that new cases of early stage breast cancer among 70-75 year olds rose sharply after national screening was introduced, from 248.7 to 362.9 per 100,000 women.
Although there was a significant fall in the numbers of new cases of advanced breast cancer, the absolute decrease was small, dropping from 58.6 before, to 51.8 cases per 100,000 women after, the national screening programme was introduced.
Among a smaller group of women aged 76 to 80, which was also included in the study for comparison as they were not screened, new cases of early stage disease fell slightly, but the numbers of new cases of advanced breast cancer did not change significantly.
For every advanced stage cancer detected by screening among 70-75 year olds, the researchers calculated that around 20 extra early stage cancers were picked up, and therefore 'overdiagnosed'.
They say this overdiagnosis is important because overtreatment can undermine quality of life, partly because older people are more vulnerable to the side effects of breast cancer treatment.
Large UK study
The authors of the study, which is published on bmj.com, recommend that routine breast cancer screening among women aged over 70 should not be performed on a large scale until the results of a large, randomised trial currently being conducted by Cancer Research UK are known.
The results of this trial are not expected for some years.
In the meantime, they say, "the harms and benefits of screening should be weighed on a personalised basis, taking remaining life expectancy, breast cancer risk, functional status, and patients’ preferences into account".
Commenting on the Dutch study in a statement, Dr Caitlin Palframan, head of policy at Breakthrough Breast Cancer, says: "This study provides some useful insights as women over 70 were not included in the original breast screening trials on which modern screening programmes are based. It's very important we learn more about the benefits and risks for this particular age group before we decide whether to offer these women routine screening."