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Making sense of the screening debate
Posted by Sile Lane on 16 August 2011
Volunteer Samantha Cheung and I have been following the recent debate about breast cancer screening.
On 28th July 2011, the BMJ published research suggesting that breast cancer screening programmes are unlikely to have directly influenced the current decline in breast cancer mortality rates in Europe. Instead, “improvements in treatment and in the efficiency of healthcare systems may be more plausible explanations.” This research was widely reported (e.g. in the Daily Mail, The Telegraph and The Sun) and has prompted lots of debate on the issue in the media: some experts called for the screening programme to be scrapped; campaign groups urged women to continue attending for screening; doctors told women to weigh up the pros and cons for themselves; and newspapers printed letters from individual women who have benefitted from screening and others who had not.
The different debates going on amongst experts and between individual women make it hard for people to make sense of screening. In 2009 there was a similar discussion about cervical cancer screening with two slightly different debates going on – individual women and campaign groups were talking about how screening saved them or let them down, while scientists and policy makers debated the merits of population wide screening programmes. We got experts together then to help us make sense of the debate. These are the insights that we found most helpful:
- Screening programmes are designed to identify the majority of people who have a disease but cannot prevent disease.
- Some false positives and false negatives are an unavoidable cost of screening people who don’t have symptoms of a disease. The potential harms and benefits must be balanced.
- Screening cannot provide a definitive yes/no answer. An “all clear” does not mean that you will never develop the disease.
- Screening rarely benefits all sections of a population so it needs to be targeted at those most likely to benefit.
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