Cancer and the NHS

By S.S. | LONDON

DURING the run-up to the 2010 general election, David Cameron claimed during the televised debates that Britain's death rate from cancer was worse than Bulgaria's. A few weeks ago he reinforced his call for public sector reform by claiming that “our health outcomes lag behind the rest of Europe”. Comparing the NHS's health outcomes to the rest of Europe or the Western world isn't limited to Cameron and co: 72 point bold headlines decrying NHS failures in cancer care seem to be a staple of tabloid editors when they lack inspiration for the front page. Columnists across the political divide happily fall back onto criticising the NHS for not doing as well as the rest of the world whenever healthcare peaks in the political news-cycle.

But much of what they say is nonsense. Last week John Appleby of the King's Fund, a health think-tank, warned that comparing the survival rates the NHS achieves with those in other medical systems was “not straightforward”. His remarks were shrugged off by the coalition, but he is right, and the reasons he is right are interesting and illuminating. Health statistics are curious creatures, cancer statistics even more so. They're deeply, heavily reliant on context to imbue them with meaning. Ripping them out of that context to use them in support of a political stance about the NHS robs them of meaning and therefore truth.

For starters, cancer statistics live and die by the method of data collection. EUROCARE-4, the most recent publication of a Europe-wide cancer death registry, claims the UK has lower survival rates for the four most common cancers - lung, breast, colon and prostate - than the rest of Europe. But only 1% of German hospitals and 15% of French ones provided data to the EUROCARE registry. However nearly every British hospital submitted data thanks to the centralised registry run by the Department of Health. Suddenly the soundbite changes from “Britain worse than Europe for cancer survival” to “Britain worse than small proportion of Europe that bothers to submit data for cancer survival”. Bad sample sizes give bad data, which gives bad statistics when you don't give their context.

Next, cancer statistics depend on how the cancer was diagnosed, which varies geographically. The World Health Organisation's World Health Statistics report 2009 says the UK has a cancer mortality of 147 per 100,000 people. The same report says Namibia has 91 cancer deaths per 100,000 people, Bangladesh has 107 per 100,000 and North Korea 95 cancer deaths per 100,000 people. Surely the NHS, one of Britain's proudest state institutions, can't possibly be worse than, of all countries, North Korea?

Britain has the most equitable access to healthcare in the world, multiple different screening programs for various cancers and pre-cancerous conditions along with strong post-mortem requirements and a high skill-set among pathologist doing those post-mortems. North Korea and Bangladesh have none of those. Patients with cancer there may lack a doctor to diagnose them before dying at home at and being buried without a post-mortem providing the diagnosis. Inevitably, this means both countries look like they have better cancer survival rates than the UK, where cancers are found during screening programs, during routine consultations and at post mortem, which artificially inflates mortality rates in comparison to less developed countries. This leads to bad statistics when this background isn't made clear.

Cancer deaths are affected by other diseases too. The average life expectancy in Namibia is 60, whereas life expectancy in Britain is 80. Cancer is mostly a disease of old age; for example the average age at diagnosis for breast cancer is 65. In Namibia people simply don't live long enough for cancer to become a leading cause of death, often dying at a younger age of preventable infections and trauma due to lack of access to care. Inevitably this means they appear to be “better” at surviving cancer than the Brits—unless, of course, you give the context.

Next, cancer is not a universal disease. There is a huge difference in the survival rate for stomach cancer between Britain and Japan which, if presented alone, makes Britain look rather bad. But stomach cancer has a much higher incidence in Japan (for poorly understood reasons), which means there is a strong nation-wide screening program to catch it early. It's a rarer cancer in the UK and a screening program wouldn't be cost effective compared to screening for other cancers that are far more common. Many British patients with stomach cancer present too late to be cured compared with Japanese patients who are caught much earlier when screened.

This runs us into the next rule: screening programs change everything for the better and for the worse. We've already seen how screening programs that exist in one country and not another can skew good international comparisons. America does cervical cancer screening every year, the UK does screening every 3 to 5 years, which means the Americans diagnose more cervical cancers. However not all cervical cancers found at screening will become fully cancerous and need treatment. There's no way to tell through the screening program which are which, so many American women are having un-necessary treatment compared to Brits. When talking about cancer diagnosis and mortality, the details of screening programs must be given otherwise the statistics lose too much context to make sense.

Finally, cancer statistics are by definition out of date by the time they're published. The EUROCARE-4 statistics involve patients diagnosed with cancer between 1995 and 1999, who were followed through to 2002 before the data was published. But in 2000 the NHS Cancer Plan was published, changing the uncoordinated mess that was British cancer care at the time into a formal, structured system with a greater emphasis on screening and on preventative programs to stop cancers from developing in the first place. The results of this plan will take years to be observed because of the time lag between a cancer first developing and eventually being diagnosed, making it meaningless to use statistics from before the plan was implemented to criticise the current system.

In an ideal world everything would be put into context and statistics would be used honestly but, until that happy day, it's wise to reflect critically whenever people make glib claims about NHS under-performance on cancer.

S.S. is a final-year medical student

When this article was first published, one of the links in the text was not working. It has now been fixed