European Journal of Cancer

Issue 5, 2008

PODIUM – Cancer trends in Europe – with Henrike Karim-Kos

Henrike Karim-Kos

Henrike Karim-Kos took a first degree in human nutrition and epidemiology at Wageningen University, the Netherlands. She worked as an epidemiologist in cancer centres elsewhere in the Netherlands before embarking on a PhD at Erasmus MC Medical Centre, Rotterdam. She is joint first author on an EJC paper, ‘Recent trends of cancer in Europe: a combined approach of incidence, survival and mortality for 17 cancer sites since the 1990s’.

How important is it to consider incidence, mortality and survival statistics together?

Many studies consider only survival – and they receive a lot of press attention. But you don’t get a complete picture of cancer trends by looking at survival alone. For example, in prostate cancer, survival rates are improving dramatically, which implies that things are going in the right direction. But incidence rates are also soaring, because of the availability of PSA testing. The case-mix now includes a lot of low stage tumours with good prognosis, and the increase in survival tells you nothing about whether treatment has improved. You have to combine the incidence and survival with mortality data. If incidence and survival are increasing and mortality hasn’t changed, you can’t assume that treatments have improved: other things like over-diagnosis might be involved. If mortality is going down, then new treatments may be having an effect. It is important to look at all 3 sets of data to get a complete overview.

What real trends did you find?

Obesity-related cancers are increasing, especially in north-western Europe, and are probably spreading to central Europe. The incidence of colorectal cancer, for example, increased slightly in most countries except those in central Europe. In a lot of countries, colorectal cancer survival increased, mortality decreased and the incidence was unchanged or slightly increased: this suggests improvements in management or treatment.

What about smoking-related cancers?

In northern and western Europe, we see declining trends in smoking-related cancers, indicating the success of anti-tobacco measures taken. There was a clear decrease in the incidence and mortality among men in these countries, but rates are now also dropping in central Europe. Among women, the incidence and mortality of smoking-related cancers is still increasing, but encouragingly, we are seeing the first signs of stability in the north and west Europe. In the UK, for example, rates are levelling off. We hope this trend will spread throughout Europe. 

Why were cancer trends in the UK and Denmark markedly worse than in neighbouring countries?

These countries still lag behind their neighbours, but they are improving and the trends are going in the right direction. The UK’s National Cancer Plan was drawn up in 2000 and it will take about 10 years to have an effect at population level; the data included in our study does not go beyond 2004. Incidence and mortality figures in the UK were similar to those in other parts of northern Europe. Survival was lower, but it is improving and the gap is closing. In both of these countries, governments have kept tight control of health care spending since the 1960s and thus there have been more limited resources. Further, Denmark had high rates of smoking among women; incidence and mortality rates from lung cancer were higher among women in Denmark than anywhere else in Europe.

Were there any unexpected results?

In cervical cancer, survival decreased. It was surprising, but in fact quite logical. Many countries have screening programmes which detect pre-malignancies (which therefore never become malignant) and slow-growing tumours which can be treated quite well. Removing pre-malignancies reduces the incidence but also means that the resulting case-mix includes proportionately more aggressive tumours with a worse prognosis. These tumours may not be detected by screening (if they appear in the screening interval). Overall, survival deteriorates, but incidence and mortality rates are decreasing! It’s another example of why it’s important to consider the 3 sets of data together.

What is happening in Central Europe?

Survival rates in central Europe have lagged behind those in the rest of Europe, but survival is definitely increasing in these countries now, and mortality is going down. The figures are becoming more like those in other parts of Europe. It’s really good news and is partly down to improvements in treatment, but also to earlier diagnosis.

What is the take-home message?

Cancer trends are going in the right direction, and survival is increasing for most cancers. Differences between countries have decreased over time. We need to keep focussing on primary prevention campaigns, such as anti-smoking (already shown to be effective) and anti-obesity campaigns. But secondary prevention such as screening and further research into better diagnostics, treatment and health care management also needs our attention to continue this positive trend.

Click here to view this paper as well as EJC's Editor-in-Chief John Smyth's comment in his Pick of the Papers, 3rd Quarter 2008.