Breast screening saves lives say experts
UK screening experts have emphasised the benefits of breast screening after a study suggested that one in three cancers detected by screening might not need treatment.
Researchers at the Nordic Cochrane Centre have claimed that up to one in three cases of breast cancer detected during routine screening may not threaten a woman's life, and would not need treatment.
Some breast cancers grow slowly, lie dormant or even regress - treating women with these tumours amounts to 'over-treatment'. However it is currently impossible to tell which tumours are aggressive and which are less harmful, so doctors offer treatment to most women.
The researchers studied breast cancer trends in five countries with national screening programmes - the UK, Canada, Australia, Sweden and Norway - and analysed rates of breast cancer before and after the introduction of the screening programmes.
Their analysis, published in the British Medical Journal, concluded that around a third of breast cancers detected through screening are treated unnecessarily.
But screening experts disagree. Writing on Cancer Research UK's blog, Professor Stephen Duffy, Cancer Research UK's professor of screening, said that he was unconvinced by the study's findings.
"There have been other studies which analysed the cancer incidence data more thoroughly and estimated much lower rates of over-diagnosis.
"We do not find the results of this study to be credible. Women should not be put off breast screening, which saves over 1,000 lives a year in the UK."
Professor Julietta Patnick, director of the NHS Cancer Screening Programmes, said: "It is estimated that breast screening saves 1,400 lives every year in England through early detection of the disease."
She pointed out that early detection increases the likelihood of treatment being effective and that screening allows cancers to be found much earlier, when they are less likely to be fatal.
So while breast screening causes some women to undergo unnecessary treatment, it undoubtedly helps other women by picking up cancers that might otherwise have gone undetected until they were at an advanced stage.
Dr Laura Bell, Cancer Research UK's science information officer, said: "The number of women dying from breast cancer has fallen to less than 12,000 for the first time in almost 40 years and this is partly due to the National Breast Screening Programme which prevents more than 1,000 breast cancer deaths every year.
"The programme is very successful at detecting the early stages of the disease which means treatment is much more effective, and we still urge women to go for screening when invited.
"But it is crucial that women are properly informed of the potential benefits and harms of breast screening. Improvements can always be made, and we are contributing to a review by the Department of Health."