According to a new study from the International Agency for Research on Cancer (IARC), one in eight cases of cancer worldwide in 2024 will be caused by infections.
This equates to 2.3 million (or 12%) of new cancer cases that year, with five infections accounting for a considerable proportion of these cases. The IARC researchers therefore said that the results suggest that a “significant proportion of the global cancer burden could be avoided through better infection control”.
The study was published in the journal Lancet Oncology on September 28.
“This fraction, one in eight cancer patients, is the same as lung cancer in all cancers in the United States. This is not a rare or insignificant problem,” said Dr. Patrick Moore, chair of innovative cancer research at the University of Pittsburgh. News weekadding that the IARC estimates could also be “very conservative”, meaning that “the actual fraction of cancers caused by infection is likely even larger”.
He said infection is “a much bigger driver of cancer than most people realize and the importance of each specific infection is strongly linked to geography.” He added that reductions in HIV treatment due to the dissolution of USAID “will lead to an increase in infectious cancers in sub-Saharan Africa, while in Asia, the expansion of neonatal HBV vaccination could significantly reduce liver cancers caused by this virus.”
Karl Munger, professor of developmental, molecular and chemical biology at Tufts University, said News week that the IARC estimate is “lower than I expected. Other analyzes have suggested that infection-associated cancers account for 15 to 20 percent of cancer cases worldwide, although the proportion is considerably lower in the United States and other high-income countries.” He added that this finding is “important because infections are an often overlooked and underestimated cause of cancer. It is important to note that many cancers associated with infections are preventable.”
Infections that caused the most cases of cancer
According to the results of the study, the main infectious causes of cancer in 2024 were Helicobacter pylori (Or H. pylori), human papillomavirus (HPV), hepatitis B virus (HBV), Epstein-Barr virus (EBV), and hepatitis C virus (HCV).
H. pylori was linked to the highest number of cases, around 760,000 cancer cases worldwide that year. These cases were mainly gastric (stomach) cancers.
HPV was associated with approximately 750,000 cases of cancer worldwide, primarily cervical cancers, as well as cancers of the anus, vulva, vagina, and penis, as well as some head and neck cancers.
HBV was linked to approximately 360,000 cases of cancer in 2024, and most were cases of liver cancer. EBV was linked to about 260,000 cancer cases worldwide that year, which were largely nasopharyngeal cancer, some gastric cancers, and Hodgkin’s lymphoma. HCV was associated with approximately 160,000 cases of cancer, most of them liver cancer.
The researchers also found that the burden of cancer cases was highest in East Asia, sub-Saharan Africa, central and eastern Europe, and Southeast Asia. Specifically, East Asia has had to bear a particularly heavy burden due to H. pylori and HBV, while sub-Saharan Africa had very high rates of HPV-related cancers and a significant burden of HIV and Kaposi’s sarcoma-associated herpesvirus (KSHV) infections.
They said regional differences likely reflect “variations in the prevalence of infections, access to prevention and treatment, and broader social and economic conditions.”
Dr. Shan-Lu Liu, co-director of the Emerging Viruses and Pathogens Program at Ohio State University, said: News week that he found the results “both striking and encouraging”.
“What is encouraging is that many of these cancers are potentially preventable through vaccination, infection control, screening and treatment,” he said. “The large geographic disparities also show that this is an important global health equity issue.”
How do infections cause cancer?
Dr Gary Clifford, a scientist at IARC and lead author of the study, said News week that many of these infections “hijack the cellular machinery that controls the normal cell cycle in order to facilitate their own replication – however, this includes hijacking the machinery that would normally repair mutated genes or instruct mutated cells to die, thereby increasing the risk of mutated cells becoming immortal, i.e. cancer.” »
Liu said several other mechanisms are also at play, such as chronic inflammation and repeated tissue damage (which can increase DNA damage and abnormal cell growth), as well as many others.
For each of the top infections, how they might lead to the development of cancer is very specific, Liu said, which is why they are each associated with different types of cancers.
Moore said that for at least five of the seven infectious diseases, “the virus itself carries oncogenes (“cancer-causing genes”) that directly cause cancer when inserted into healthy cells,” which, he added, “causes the cell to proliferate under the right conditions, such as immune suppression.”
Does this mean that some cases of cancer are preventable?
Clifford said the findings “demonstrate that a large proportion of cancers are caused by known infectious causes and are therefore preventable.”
He also said that cancers “caused by infectious agents have proven particularly easy to prevent (compared to cancers caused by other lifestyle risk factors), given the ability to vaccinate, test and treat underlying infections,” making them “highly actionable targets.”
However, IARC researchers said that while there are already many effective prevention tools against these infections, including vaccination against HPV and HBV, screening and treatment for infections such as H. pyloriHBV, HCV and HIV, as well as measures to prevent transmission, these interventions are “often underutilized or inaccessible, particularly in low- and middle-income countries, due to financial, social and political barriers.”
They said key challenges that remain include “limited access to vaccination, testing, diagnosis and treatment of infections, and social stigma related to infections such as HPV and HIV.”
“In some contexts, prevention programs are also affected by financial constraints, insufficient political commitment and inequitable access to care,” they said.
What should happen next?
IARC scientists said policymakers and health systems should prioritize scaling up proven interventions in light of results, such as vaccination against HPV and HBV; tests and treatments for H. pyloriHBV, HCV and HIV; measures to prevent transmission, such as safe injection practices, access to condoms and HIV pre-exposure prophylaxis; and cervical cancer screening.
Liu also said he believes “we need to expand vaccination and make testing and treatment for persistent infections more accessible,” as well as strengthen cancer screening in high-risk populations and improve access to low- and middle-income countries where most of the infection-related cancer burden occurs.
Reference
Rumgay H, Georges D, Huang Y, Hirabayashi M, Shah R, de Martel C et al. (2026). Global cancer burden attributable to infections in 2024: an analysis of global incidence. Lancet Oncology. https://doi.org/10.1016/S1470-2045(26)00307-4
Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang
Updated 9/25/26, 3:13 p.m. ET: This article has been updated with comment from Karl Munger.
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