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Bowel cancer rates vary 10-fold worldwide

Rising rates link to economic development, says study

Adrian O'Dowd

Wednesday, 03 February 2016

The numbers of new cases of bowel cancer and deaths from the disease vary 10-fold across the world, concludes research* published online in the journal Gut.

Researchers led by Dr Melina Arnold of the Section of Cancer Surveillance, International Agency for Research on Cancer, Lyon, France, also found that international bowel cancer patterns and trends seem to be linked to economic development.

Bowel cancer is the third most commonly diagnosed cancer and the fourth leading cause of cancer death in the world. In 2012, there were an estimated 1.4 million new cases and almost 700,000 associated deaths worldwide.

By 2030, experts are predicting that the numbers of new cases are expected to rise to 2.2 million with an associated death toll of 1.1 million.

The researchers set out to provide a picture of the international distribution of bowel cancer and the prospects for curbing predicted rises in rates.

They extracted data from the GLOBOCAN database on the numbers of new cases and deaths from the disease in 2012 for 184 countries.

In addition, they also looked at time trends in 37 countries, using data from 10 volumes of Cancer Incidence in Five Continents and the World Health Organization (WHO) mortality database.

Results showed that the estimated rates of new cases in 2012 varied from less than 5 per 100,000 of the population in several African countries to over 40 per 100,000 in certain countries in Europe, Northern America, and Oceania.

Rates in women tended to be around 25% lower than those of men. Amongst men, the highest rates were in Slovakia (61.6), Hungary (58.9), and Korea (58.7) while the lowest rates (1.5/100,000) were in sub-Saharan Africa, The Gambia, and Mozambique.

Using information from the United Nations Development Programme, bowel cancer rates were analysed across levels of economic development, referred to as the HDI, for 2012 in all 184 countries.

The researchers found that the higher the HDI, the higher was the incidence of bowel cancer.

In countries with a very high HDI, the number of new cases was, on average, six times higher than in countries with a very low HDI.

Patterns of deaths from the disease were similar to those of incidence, although the highest rates tended to be in countries with high, rather than very high, HDI, in central and eastern Europe and in Latin America.

The study was observational, so did not prove cause and effect, but the authors said: “The fact that [bowel cancer] has replaced infection-related cancers as the second most common cancer in several middle income countries (particularly among women) highlights the major challenge of [bowel cancer] control in countries undergoing significant socioeconomic transition.

“Without targeted resource dependent actions based on this evidence, the number of patients with bowel cancer will continue to increase in future decades beyond those already projected as a result of population ageing and population growth.”

* Arnold M, et al. Global patterns and trends in colorectal cancer incidence and mortality. Gut, Published Online First 27 January 2016. doi:10.1136/gutjnl-2015-310912

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