Progress in detecting breast tumours at an early stage may have stalled this century, a European conference will hear today.
Researchers linked the introduction of breast screening last century to a significant reduction in the size of tumours found at first diagnosis.
But the study found that tumour size at first diagnosis has been increasing since 2001. This may be linked to a reduction in take-up of breast screening, the researchers say.
The British researchers, from Weston-Super-Mare, Somerset, analysed data from the USA to study trends in tumour size at first diagnosis.
They are reporting their findings to the European Breast Cancer Conference in Barcelona, Spain.
They analysed nearly 400,000 women in the USA diagnosed with breast cancer between 1983 and 2014.
The found an overall reduction of 23% in average tumour size during the period. But since 2001, the size of these tumours has increased by 13% in women diagnosed in their early 50s, they found. And there has been a small increase – of 3% – in tumour size in women in their early 70s.
Researcher Dr Manon Jenkins said: “Rates of breast cancer survival have been improving steadily thanks both to the introduction of screening and to improvements in treatments. What we don’t know is which has played the biggest role in improving survival.
“This study suggests that by reducing tumour size, screening provides a platform from which breast cancer treatments might work more effectively.
“The recent increase in the average size of tumours may reflect a decline in rates of screening. If this is followed by a deterioration in breast cancer mortality rates it would strengthen the argument for screening programmes to continue.”
Conference chair Professor Robert Mansel, of Cardiff University medical school, UK, said: “This study suggests there has been an overall decline in the average size of breast tumours since screening was introduced and we know that smaller tumours do lead to better prognosis.
“The research also shows that the decline has been less pronounced in older women and that, more recently, there has been a slight increase in average tumour size overall. Both of these are of concern, and we will need to continue to monitor breast screening programmes and their impact on survival in women of all ages.”
Abstract no: 14. Changes in tumour diameter since the introduction of breast cancer screening: an observational study from the SEER database between 1983 – 2014
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