About one in eight cancers diagnosed worldwide in 2024 was caused by an infection, according to a major study by the World Health Organization's cancer research arm. The analysis, published in The Lancet Oncology on September 29, estimates that about 2.3 million new cancer cases were linked to infections that year.Five pathogens caused almost all of the burden. The stomach bacterium Helicobacter pylori was linked to 760,000 cancers, mostly stomach cancer in eastern Asia. Human papillomavirus, or HPV, was tied to about 750,000 cases, led by cervical cancer. Hepatitis B caused about 360,000 liver cancers, Epstein-Barr virus about 260,000, and hepatitis C about 160,000.The researchers stressed that many of these cancers are preventable. Vaccines, screening and treatment for the underlying infections can stop cancer before it starts. Low- and middle-income countries carry about three-quarters of the infection-linked cancer burden.Study senior author Gary Clifford of the International Agency for Research on Cancer said prevention works but needs political will, funding and public awareness. The study examined 12 infectious agents classified as definite causes of cancer.