I wrote recently about the vagaries of over-diagnosis. Here is a piece on a breast cancer screening from the Daily Telegraph I thought was interesting. Of course, I am not saying don’t get screened, but I, for one, am becoming more aware of the debate:
Daily Telegraph: By Stephen Adams, Medical Correspondent 29.7.11
“Breast cancer screening programmes have “little detectable impact” on reducing death rates from the disease, a study claims today.
A group of international cancer experts say they can find no evidence that mammogram x-ray screening has led to faster falls in deaths rates from breast cancer. One independent researcher last night said governments “seriously have to consider” dropping breast cancer screening programmes.
For the study, published in the British Medical Journal, falls in breast cancer death rates were compared in three pairs of similar territories: Northern Ireland to the Republic of Ireland; Sweden to Norway; and The Netherlands to Flanders in Belgium.
In the first of each pair, screening was introduced 10 to 15 years earlier than in the second. However, they found little difference between the pairs in breast cancer mortality rate falls from 1989 to 2006.
The percentage drops were as follows: Northern Ireland 29, Republic of Ireland 26; Sweden 16, Norway 24; Netherlands 25, Flanders 25.
The similarities “suggest that screening did not play a direct part in the reductions in breast cancer mortality”, they concluded.
Their study added to others which “found that mammography screening by itself has little detectable impact on mortality due to breast cancer”. Improvements in treatment and healthcare systems “may be more plausible explanations” for death rate falls, they found.
Dr Karsten Juhl Jørgensen, of the Nordic Cochrane Centre in Denmark, said the paper drew similar conclusions to one he had co-authored with colleague Prof Peter Gøtzsche, published in the BMJ last year. It found breast cancer death rates fell slower from 1997 to 2006 in areas of Denmark where screening had been introduced in 1991. He said it was “becoming increasingly clear” that those who deserved the credit for falling death rates “are those who treat breast cancer, not those who screen healthy women”.
Last year the same Nordic Cochrane Centre team claimed that 7,000 women a year in Britain were undergoing unnecessary treatment – including mastectomies – after wrongly being told they had life-threatening breast cancer. The problem is that mammograms detect both tumours and pre-cancerous legions in milk ducts called ductal carcinoma in situ (DCIS). If left untreated half DCISs will develop into cancer while half will not. Dr Jørgensen said: “We are turning thousands of healthy women into breast cancer patients, who will be worried about a non-disease returning for the rest of their lives. That’s something we should be avoiding.” He believed health ministers “seriously have to consider” dropping breast cancer screening.
However, Dr Anna Gavin, one of the authors of today’s study, and director of the Northern Ireland Cancer Registry, said she still had confidence in screening. “If someone is invited, they should go,” she said. “But we do need to question screening and be sure that the benefits outweigh the risks.”
- Women ‘should be offered ultrasound breast cancer screening’ – 04 Oct 2010
- Breast cancer screening benefits questioned – 19 Jan 2010
- Breast cancer screening has ‘little impact’ (telegraph.co.uk)