Cancer survival is complicated

“Your chances of surviving from cancer, in America, if you are diagnosed with cancer, is better than in the UK.”

Mark Littlewood, BBC Question Time, 13 October 2011.

 

I was recently an audience member at a recording of BBC Question Time in East London – a deeply frustrating experience.

I’ll save discussion of panelist Mark Littlewood’s assertion that increased choice in the NHS would lead to reduced health inequalities for another time  – what data there is suggests less educated people reliant on public transport aren’t as likely to exercise their choices. I’ll also leave for now Andrew Lansley’s claim that the Health Bill is not about increasing competition.

I will, instead, examine Mark Littlewood’s claim about cancer survival.

Those seeking support for the Health Bill have made a concerted effort to rubbish NHS cancer care over recent months. The most outrageous example of this was David Cameron’s assertion, in the run up to the last election, that “our death rate from cancer is actually worse than Bulgaria’s.”

Stephen Henderson commented at the time, “I’m reluctant usually to rely on anecdotal evidence, I‘ve been in a Bulgarian hospital and I’m pretty confident that their low cancer mortality has nothing to do with standards of care.” 

It is instructive to review once again why Cameron and Littlewood may be right, and why that tells us little about the state of NHS cancer care. This is not new ground, as it has been covered in recent months by Rob Aldridge, Ben Goldacre, and Cancer Research UK. However, I think the ideas are worth reiterating.

Mortality and survival rates are not the same. Exposure to risk factors has a major effect on incidence and therefore on mortality from cancer even where survival remains unchanged. Cancer mortality is falling rapidly in the UK.

The data most widely cited in this debate describes cancers diagnosed before the NHS Cancer Plan was implemented.

There is variation in the proportion of cancer cases included in national registries. The UK data is fairly complete. In the US, only a quarter of cancers are included in the main cancer registry. Historically, disadvantaged groups have been under-represented in the sample, a problem given poverty is correlated with poor survival.

Finally, cancer survival depends on when disease is diagnosed. For example, in the US, the PSA blood test is more widely used meaning many men are diagnosed very early with prostate cancer. Whilst this increases cancer survival rates, most people with prostate cancer die with rather than of their disease. Many American men will have been exposed to unnecessary anxiety and potentially unnecessary treatment. A similar argument can be made regarding UK-Europe comparisons of breast cancer survival rates.

I have no idea how familiar Mark Littlewood is with the literature on cancer survival but, given how much is at stake in these NHS reforms, it would be helpful if he could qualify the remarks he made on cancer survival in a public forum.

A version of this blog was originally posted at BMJ.com.