One in six cancer cases worldwide is caused by an infection, according to estimates from a new study.
Of the 12.7 million cases of cancer that occurred in 2008, about 2 million, or 16 percent, were caused by an infectious agent such as human papillomaviruses (HPV), hepatitis B virus, and Epstein-Barr virus, the study found.
Most cases of infection-related cancer are preventable, the researchers say. For instance, available vaccines protect against major strains of HPV, which causes cervical cancer, and against hepatitis B, which can cause liver cancer.
The majority of infection-related cancer cases occur in less developed regions of the world, the study found.
Cancer is typically considered a noncommunicable disease (something you cannot "catch"), but "a sizable proportion of its causation is infectious," the researchers write in the May issue of the journal The Lancet. Approaches to preventing and controlling cancer that treat it only as a noncommunicable disease will not be sufficient, the researchers said.
The researchers, from the International Agency for Research on Cancer in Lyon, France, used data on the incidence of 27 cancers in 184 countries.
The fraction of infection-related cancers varied widely around the world, from 3.3 percent in Australia and New Zealand and 4 percent in North America, to 32.7 percent in sub-Saharan Africa. About 23 percent of cancers in developing countries are caused by infectious agents, compared with 7.4 percent in developed countries.
Helicobacter pylori bacteria (which infect the gut), hepatitis B and C viruses and human papillomaviruses were responsible for 1.9 million cancer cases.
About half of all cases of infection-related cancer in women were cases of cervical cancer.
The findings show "the potential for preventive and therapeutic programs in less developed countries to significantly reduce the global burden of cancer and the vast disparities across regions and countries," Dr. Goodarz Danaei, of the Harvard School of Public Health in Boston, wrote in an editorial accompanying the study.
"Since effective and relatively low-cost vaccines for HPV and [hepatitis B] are available, increasing coverage should be a priority for health systems in high-burden countries," Danaei said.
Pass it on: Two million cases of cancer worldwide are caused by largely preventable infections.
Sign up for the Live Science daily newsletter now
Get the world’s most fascinating discoveries delivered straight to your inbox.