Screening 'overdiagnoses one in three breast cancers'
By Steve Nowottny
One in three breast cancers detected by public breast screening programmes could safety go untreated, according to a paper published in the BMJ today.
Researchers at the Nordic Cochrane Centre analysed breast cancer trends before and after the introduction of publicly organised screening programmes in five countries, including the UK.
Taking into account other factors which may have affected the results, such as changes in background levels of breast cancer and any compensatory drop in breast cancer rates among older, previously screened women, they estimated an overdiagnosis rate for invasive breast cancer of 35%.
Writing in the BMJ, authors Karsten Jorgensen and Peter Gotzsche said: ‘Screening for cancer may lead to earlier detection of lethal cancers but also detects harmless ones that will not cause death or symptons.'
‘The detection of such cancers, which would not have been identified clinically in someone's remaining lifetime, is called over-diagnosis and can only be harmful to those who experience it.'
But Professor Julietta Patnick, director of the NHS Cancer Screening Programmes, accused the researchers of a ‘highly selective' use of statistics, saying the paper took no account of lifestyle changes which had increased the incidence of breast cancer in England.
‘Thanks to screening, one extra woman's life will be saved for every eight women diagnosed with breast cancer,' she said.
‘By bringing forward the date of diagnosis, through early detection, we find those cancers that would otherwise not be caught until later in life, by which time they could be fatal.'
‘Without this early detection, screening would not work. It is estimated that breast screening saves 1,400 lives every year in England through early detection of the disease.'