Where viruses and bacteria cause cancer Strictly speaking,
cancer is not contagious. But a fair number of cancers are
clearly caused by viral or bacterial infections: lymphomas can
be triggered by the Epstein-Barr virus, which also causes
mononucleosis. Liver cancers can be caused by Hepatitis B and C.
Cervical cancers can be caused by human papillomavirus, the
major reason behind the development of a vaccine against it. For
some of these cancers, nearly 100% of the cases have an
infectious link—when researchers check to see if a virus or
bacterium is working in the tumor or has left signs of its
presence in a patient’s blood, the answer is nearly always yes.
A new paper in The Lancet takes a look at the very best data on
the prevalence of infection-caused cancers and comes up with
some striking numbers. Overall, they estimate that 16% of cancer
cases worldwide in 2008 had an infectious cause—2 million out of
12.7 million. The war between people and disease-causing
pathogens is old as humanity itself. This ha