Four Bad Actors Cause Most Infection-Related Cancer

Nick Mulcahy

May 08, 2012

May 8, 2012 — Three types of viruses and 1 bacterium cause the vast majority of the new cases of cancer worldwide that are attributable to infections, according to a new study of global data.

The study found that in 2008 there were 12.7 million new cases of cancer worldwide, including 2 million that were related to infections. Helicobacter pylori, hepatitis B and C viruses (HBV and HCV), and human papillomaviruses (HPV) were responsible for 1.9 million of those infection-related cases.

Most of these new cases were gastric, liver, and cervix uteri cancers, according to study authors, who are from the International Agency for Research on Cancer in Lyon, France.

Their study is published online in the May 8 issue of Lancet Oncology.

The study authors, led by Catherine de Martel, MD, PhD, point out that the situation is largely remediable.

"Application of existing public-health methods for infection prevention, such as vaccination, safer injection practice, [and] antimicrobial treatments, could have a substantial effect on future burden of cancer worldwide," they write, referring to prevention measures for HBV and strains of HPV, HCV, and H pylori, respectively.

An expert not involved with the study emphasized the value of vaccination.

"Since effective and relatively low-cost vaccines for HPV and HBV are available, increasing vaccine coverage should be a priority for health systems in high-burden countries," writes Goodarz Danaei, MD, ScD, in an accompanying comment. He is from the Harvard School of Public Health in Boston, Massachusetts.

However, neither the study authors nor Dr. Danaei say where the funds will come from for this important prevention work.

The study indicates that less developed countries were 3 times as likely as more developed countries to have infection-related cancers.

The authors report that, in 2008, 1 in 6 (16%) new cases of cancer were related to infection. "This fraction was higher in less-developed countries (22.9%) than in more-developed countries (7.4%), and varied from 3.3% in Australia and New Zealand to 32.7% in sub-Saharan Africa," they note.

Dr. Danaei put the problem of infection-related cancers into a larger epidemiologic context.

"The estimated attributable fraction for all infections combined was 16.1% — by comparison, in 2004 WHO estimated the attributable fraction for the combined effect of 9 lifestyle and environmental risk factors as 35%," he writes, referring to smoking, drinking alcohol, excess weight, and other factors.

The authors report that cervical cancer accounted for about 50% of the infection-related burden of cancer in women, and liver and gastric cancers accounted for about 80% of the burden in men.

Cancers and Infections

de Martel and her colleagues did a systemic analysis to estimate the proportion of cancers that could be tied to infection globally and in 8 regions by calculating the population-attributable fractions. This refers to the proportion of new cancer cases in a population that could have been prevented by an intervention on a specific exposure.

They used data from a number of sources, including GLOBOCAN statistics on incidence estimates for 27 cancers in 184 countries.

Cancers and Their Associated Infectious Agents Covered in the Study

Cancer Associated Infectious Agents
Stomach H pylori
Liver HBV, HCV, Opisthorchis viverrini, Clonorchis sinensis
Cervix uteri HPV with or without HIV
Anogenital (penile, vulva, vagina, anus) HPV with or without HIV
Nasopharynx Epstein-Barr virus (EBV)
Oropharynx HPV with or without tobacco or alcohol use
Kaposi's sarcoma Human herpes virus type 8 with or without HIV
Non-Hodgkin's lymphoma H pylori, EBV with or without HIV, HCV, human T-cell lymphotropic virus type 1
Hodgkin's lymphoma EBV with or without HIV
Bladder Schistosoma haematobium

HIV was not listed as primary infectious agent because it causes cancer through immunosuppression, and is thus is considered a cofactor.

The study was supported by funding from the Fondation Innovations en Infectiologie and the Bill & Melinda Gates Foundation.

Lancet Oncol. Published online May 8, 2012. Abstract, Comment


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