WEEKEND COLUMNISTS I am reporting good news, for a change. The UK Breast Screening Service has said it intends to rip up the leaflet which is currently sent to women with breast screening appointments. A recent paper in the British Medical Journal outlined the kinds of uncertainties and likelihoods the authors thought would have counted as “fair information” to give to women. This seems to have prompted UK Breast Screening to review the content of its leaflet and try to give better information.
I am a GP, and so my perspective on what is “better” will likely take account of the difficulties which I observe breast screening leading to. My wish list starts with wanting the new leaflet to describe screening explicitly as an intervention which one can accept or decline. Breast screening should not be something which is sold, or which one is persuaded or coerced into. Women should be treated as competent adults who have the pros and cons explained to them: it is simply not ethical for breast screening to proceed without proper counsel.
People have written entire books about the problems of screening. I will stick to just two things: “overdiagnosis” of what is sometimes called “pseudodisease”, and limited gain. “Overdiagnosis” relates to the fact that it’s not just full-blown cancers that are detected. Some of the abnormalities seen and biopsies examined can represent situations where the prognosis is uncertain. Some of these are a condition called “ductal carcinoma in situ”. This makes up about 20 per cent of “breast cancer” diagnosed at screening in the UK. While these are commonly treated with surgery and possibly chemotherapy and radiotherapy, only a minority may end up progressing to a life-threatening cancer. Studies done at autopsy imply that 15 to 39 per cent of women die with, rather than from, this type of cancer.
The most recent systematic review of breast screening has concluded that if 2,000 women are screened regularly for 10 years, one will avoid dying of breast cancer. Ten other healthy women will be treated for breast cancer found at screening but will not benefit from treatment, as they were never going to die from the disease. And out of the 2,000 women screened, 200 will have a “false alarm”. They will be recalled for more tests, before they are told they don’t have breast cancer.
This is simply information: it doesn’t tell you what you should decide. You might also have been told screening can reduce the risk of dying of breast cancer by between 15 and 20 per cent. That is also true, but it is a relative, not an absolute, risk reduction. Expressing the pros and cons using more transparent statistics might make the advantages less impressive. But it is a fairer, more balanced description. And thus, it is on my wish list too.
Margaret McCartney is a GP in Glasgow
For lively discussion of the latest medical issues go to Margaret McCartney’s blog at blogs.ft.com/mccartney
