Infections Are an Important Source of Cancer

It is convenient to divide causes of death into communicable/infectious disease and degenerative diseases. In general, communicable disease kills younger people more than older people, whereas degenerative diseases are the kinds of things that kill older people. Researchers are increasingly discovering, however, that certain kinds of infectious diseases are actually the cause of certain kinds of cancer. If one doesn't kill you, the other might. A new study published in The Lancet Oncology by a French research team, and reported in places such HuffingtonPost, estimates that 2 million cancers each year in the world are caused by infections, especially human papillomavirus (HPV), hepatitis B and C, or Helicobacter pylori.

For men in particular, 80 percent of the infection-related cancers were liver and gastric cancers. In women, about half of the infection-related cancers were cervical cancer, according to the study.
"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," the researchers wrote in the study.

Especially striking, though, is that infections are a much more important source of cancer in developing countries than in developed countries.

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.

And equally striking is that around 30% of infection-attributable cases occur in people younger than 50 years. If you put these findings together you can see that the populations in the world that are already most susceptible to infections--younger people in developing countries--are those most susceptible to having an infection lead to cancer.