It will remain to be seen whether or not the release of 25 year follow-up data from the Canadian National Breast Screening Study will prove to be a game changer, but what if it did? What if its findings – that regular screening mammograms have no impact at all on mortality from breast cancer, and result in harm from an overdiagnosis rate of 22% – were proved to be irrefutably true? What then? Would we have the nerve to act? Could we ever give up the UK screening programme?
There can be no doubt that if the Canadian study were the only research available then mammography could not be recommended – we would conclude that it does more harm than good and be done with it. We should never rely on one study, of course, and other studies have shown routine mammography in a more favourable light. It is, however, the only study of significant size to be undertaken in the modern context of more effective breast cancer treatment and it is not the only time in recent years that mammography has been brought into question. So what if we were to believe its results?
What would happen if the UK National Screening Centre (UKNSC) were to withdraw its support for breast screening? We are used to new programmes being introduced, but not an established one being cancelled; after 35 years of endorsement and public health advice exhorting women to take part in screening, it would be quite an about-face to tell the population that it wasn’t such a good idea after all.
There would be all the mobile screening units for starters – what would we do with them? Replace the x-ray machines with ultrasounds and expand the aortic aneurysm programme? Cut our losses and sell them off to a haulage company? What about all the staff involved in delivering the programme? The expertise the NHS has required in reading mammograms? There would still be a role for the x-ray in symptomatic women, but there would be huge over-capacity if the screening programme were to be stopped in its tracks. I’m certainly not rushing out to buy shares in a company that makes mammography equipment.
More of an issue, though, is the political challenge that any change in policy would encompass. It is well known that no matter how compelling the argument might be for closing a hospital, trying to actually do such a thing is usually akin to political suicide – would the same be true for whichever unfortunate cabinet minister was left to announce the cessation of screening mammograms? Would the move be seen as anti-women? What would the pro-screening lobby have to say? There are enough men who are angry about being ‘denied’ a national prostate screening programme despite the evidence that it would do more harm than good. The belief that early is always better, and knowledge is always good are so deeply ingrained that they are often maintained despite any amount of evidence to the contrary.
Any woman who has had to endure the rigours of treatment for a breast cancer picked up on a mammogram can be expected to believe wholeheartedly that the whole process has saved her life – how else could anyone face going through such difficult treatment? What, then, is she to think if she hears of other women being denied the same chance to live? Can we expect everyone to make a clinical assessment of the evidence on such an emotive issue as breast cancer?
Perhaps the biggest hurdle of all, however, will be the NHS Mandate. Enshrined within this document is a drive to bring down five-year cancer survival rates; those figures that are thrown at the NHS from time to time as the UK is told how poorly we compare with the rest of Europe. The best way to keep five-year survival figures low is to concentrate on screening – catch it earlier, survive longer – and not to worry too much about mortality rates. If the Government ever sanctioned the cessation of the breast screening programme we would slip even further down the league tables and the goals of the Mandate would be harder to reach – even if it was better for the health of the nation, this could be too much for those in power to stomach.
I don’t know where the evidence will move from here – more studies perhaps? Another Cochrane review? Perhaps the UKNSC will deliver a verdict. What really matters, though, is whether we could ever act on the findings; if we have been doing the wrong thing for the last 35 years, could we ever find the nerve to change?
Dr Martin Brunet is a GP in Guildford and programme director of the Guildford GPVTS. You can tweet him @DocMartin68
