These common infections can cause cancer. Here’s what can lower your risk.
Recent research indicates that infectious diseases cause about 12 percent of new cancer cases.
October 14, 2026 at 5:00 a.m. EDT

By Daniel Wu
About 12 percent of new cancer cases worldwide in 2024 were caused by infectious agents such as viruses and bacteria, according to a recent study by the International Agency for Research on Cancer.
That means a sizable share of the cancer burden around the world is preventable with tools we already have, including vaccines and other preventative measures, researchers said.
“We have very actionable targets,” said Gary Clifford, a cancer epidemiologist and one of the authors of the study that published in the Lancet Oncology. “We have very many tools against these viruses already.”
Several infectious diseases, like the human papillomavirus and Epstein-Barr viruses, have known links to cancer. Viruses and other infectious diseases can cause cancer several ways: by causing mutations in cells’ ability to reproduce, inducing chronic inflammation and weakening the immune system.
“Viruses are not designed or evolved to cause cancer,” Clifford said. “But it can be a side effect.”
What infections were most often connected with cancer?
Recent research has expanded the range of cancers associated with some infectious diseases and microorganisms, experts said. The recent study incorporated cancers associated with HIV, which has been linked to a rare eye cancer and heightens the cancer risk from other infections. The Epstein-Barr virus, once mostly linked to a rare type of head and neck cancer, has also been associated with stomach cancer.



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