When we think about what causes cancer, what often comes to mind is tobacco smoke, family history, or unhealthy behaviors.
But certain infections can lead to cancer as well.
About 1 in 6 cancer cases around the globe are caused by preventable or treatable infections, according to a new study in the journal The Lancet Oncology.
When people become infected with certain viruses, bacteria or parasites, it can sometimes lead to cancer. According to the researchers, about 2 million people worldwide developed cancer in this way in 2008. About 80 percent of these cases occurred in developing countries.
The four infections that were responsible for most of these types of cancers were HPV or the human papillomavirus; Hepatitis B and C viruses, and the stomach bacterium Helicobacter Pylori. Women and men differed in the kinds of common cancers they got because of infections.
Cervical cancer made up about half of infection-linked cancers seen in women. In men, more than 80% of cancers tied to infection were liver and gastric cancers. Experts say low-cost vaccines and other treatment strategies, often not readily available in the developing world, could help reduce some types of infections; and that would bring down cancer rates.
In the U.S. it is recommended that children be vaccinated for the HPV and Hepatitis B viruses.