Infection Behind One Sixth Of Cancers Worldwide
Infections with certain bacteria, viruses and parasites have already been cited as strong risk factors for specific cancers, write the authors in their background information. This latest study updates the estimated influence that these risk factors have on the worldwide incidence of cancer.
The lead authors of the study were Dr Catherine de Martel and Dr Martyn Plummer from the International Agency for Research on Cancer (IARC), in Lyon, France.
Dr Christopher Wild, the Director of IARC, said in a statement:
"This study highlights the need for cancer control priorities to be set on a national and regional basis in light of the burden of infection-related cancers, particularly in the low- and middle-income countries".
For their analysis, de Martel, Plummer and colleagues examined data on global cancer incidence for 2008. They used the IARC classification of infectious agents that are linked to cancer.
Their results show that worldwide, 2 million, or 16.1% of the 12.7 million total new cancer cases in 2008 were due to infections.
Most of these cancer-causing infections were of the gut, liver, cervix and uterus.
They also note that most of the infection-related cancers are preventable, particularly those linked to the bacterium Helicobacter pylori, the hepatitis B and C viruses, and human papillomaviruses.
Between them, these four agents are responsible or 95%, or 1.9 million of infection-related cancer cases, say the researchers.
The proportion of such cancer cases is some three higher in less developed countries (22.9%) than more developed countries (7.4%).
And within this overall picture there is a huge variation by region: for instance only 3.3% of new cancer cases were due to infection in Australia and New Zealand, compared to 32.7% in sub-Saharan Africa.
The researchers found that worldwide, cancer of the cervix and uterus are responsible for about half of the new cancer cases due to infection in women, while liver and gut cancers account for more than 80% of infection-related new cancer cases in men.
About 30% of new cancer cases caused by infection occur in persons younger than 50 years, they add.
Vaccines are available to protect against hepatitis B, known to cause liver cancer, and human papillomavirus (HPV), which is linked to cervical cancer.
Also, antibiotic treatment can clear the gut of H. pylori bacteria.
The authors conclude that:
"Application of existing public health methods for infection prevention, such as vaccination, safer injection practice, or antimicrobial treatments, could have a substantial effect on the future burden of cancer worldwide."
They note that the "2011 UN high-level meeting on non-communicable diseases highlighted the growing global agenda for prevention and control of non-communicable diseases", and that although cancer is not classed as a communicable disease, "simple noncommunicable disease paradigms will not be sufficient" to deal with it, since much of the incidence can be linked to preventable and treatable infections.
In an accompanying comment, Dr Goodarz Danaei from Harvard School of Public Medicine in Boston, in the US, writes more priority should be given to increasing the coverage of low-cost vaccines like those for HPV and hepatitis B, especially in high-burden countries.
Funds from the Fondation Innovations en Infectiologie (FINOVI) and the Bill & Melinda Gates Foundation (BMGF) helped pay for the research.
Written by Catharine Paddock PhD