Breast Cancer Screening - What Does the Future Hold?

03/11/2011 11:21 GMT | Updated 03/01/2012 10:12 GMT

Last week saw the increasingly controversial subject of breast cancer screening hit the headlines once again.

The decision to launch a review into breast cancer screening policy, revealed in the BMJ by Professor Mike Richards, National Clinical Director for Cancer and End of Life Care, was in part triggered by an open letter from Susan Bewley, Professor of Complex Obstetrics at Kings College London. In her letter, Professor Bewley voiced her concerns over the evidence base supporting breast cancer screening.

At first glance, the case for screening for breast cancer is a no-brainer. Mammography offers the promise of revealing early stage cancer - and the chance to treat it before it becomes more advanced. Treatment involves a partial or full breast removal (mastectomy), and possibly chemotherapy or radiotherapy.

This has to be a good thing, right? Many certainly think so. It has been NHS policy to offer screening to women since 1988. At the moment, women between the ages of 50 and 70 are offered mammograms every three years - and this is being extended to women in between the ages of 47 and 73.

The national screening programme is seen as a triumph by many, and has been estimated by the Cancer Screening Programme to save some 1400 lives a year. Yet, as Professor Bewley points out, this and other figures from the programme have faced criticism in the academic press.

The issue with mammograms, and in fact any type of medical screening, is the risk of over detection. How can you be sure which tumours are potentially dangerous, and which ones will remain harmless if left undisturbed, or worse, are not tumours at all?

The stakes are high: get it right, and you could save lives; get it wrong and you put a healthy woman through unnecessary and traumatic surgery, not to mention the worry and stress a cancer diagnosis brings for both herself, family and friends.

It's a tricky question, and to answer it you need a lot of data. And this is part of the problem. While there have been several large-scale studies in this area, the results don't match. Nevertheless, there is now a growing body of respectable evidence that casts doubt on the benefits of screening.

Coincidentally, one such study was published in the Archives of Internal Medicine this week. Conducted by researchers from the Dartmouth Institute of Health Policy and Clinical Practice, their findings suggest that only one in eight (13%) women with screen-detected cancer has had their life saved as a result.

This figure certainly gives pause for thought. Yet for every seven instances of unnecessary worry and procedure, the eighth live is saved. And you can be sure Ms number 8 doesn't regret screening.

In his response to Prof Bewley, Mike Richards has announced a review of breast screening policy in the UK. Regardless of the outcome, the focus of health policies must be backed by the evidence.

For sure, the idea of screening is critical. Accurately detecting and treating disease before it affects our health is the 'Next Big Thing' in healthcare - where it will rank alongside some of the greatest achievements of modern medicine. In the next few years we are likely to see genetic testing become more and more useful in screening.

But just as critical is the issue of informed choice. The lack of detail about the risks of screening in information leaflets is disturbing. Certainly explaining the risk of both cancer and false positives can be challenging, but giving patients (or potential patients) the information they need to make their own decision is vital.