Key Takeaway:
- 2.3 million cancer cases in 2024 were linked to infections, about 12% of global cases.
- H. pylori and HPV accounted for more than 1.5 million infection-related cases combined.
- Vaccination, screening, and treatment could prevent hundreds of thousands of future cancer cases.
A new study finds infections caused about 2.3 million cancer cases worldwide in 2024, highlighting prevention through vaccines, screening and treatment for infection-related cancers.
Researchers published the findings in The Lancet Oncology, estimating that infection-related cancers accounted for 12% of all cancer diagnoses globally. Most of the cases were linked to infections that can be prevented or treated.
Gary Clifford, the study’s senior author and an epidemiologist at the International Agency for Research on Cancer, said prevention efforts can stop infections before they contribute to cancer.
“We can intervene before it gets anywhere near cancer,” Clifford said, adding that effective prevention requires political support, funding, public participation and clear communication.
H. Pylori And HPV Drive Global Cancer Burden
The researchers found that Helicobacter pylori, commonly known as H. pylori, and human papillomavirus, or HPV, were responsible for more than 1.5 million cancer cases combined in 2024.
H. pylori was primarily associated with gastric cancers, while HPV was predominantly linked to cervical cancer. Hepatitis B virus, or HBV, accounted for an estimated 360,000 cases, mostly liver cancers.
Epstein-Barr virus, or EBV, was associated with about 260,000 cases, with nasopharyngeal cancer as the main contributor. Hepatitis C virus, or HCV, was linked to about 160,000 cases, primarily liver cancers.
Harriet Rumgay, an epidemiologist at the International Agency for Research on Cancer and an author of the study, said some infection-related cancers have poor outcomes and that infection is necessary for the development of some others.
“Highly effective prevention measures already exist for four of the five leading infectious causes of cancer, as well as for HIV,” Rumgay said.
Researchers analyzed data from the Global Cancer Observatory’s Cancer Today database to estimate global cancer incidence in 2024 and identify cases attributable to infections. The analysis included 16 additional infection-cancer pairs compared with a 2018 global assessment.
Low- And Middle-Income Countries Carry Most Cases
Low- and middle-income countries accounted for 77% of infection-attributable cancer cases, the study found. Researchers said differences in infection prevalence and access to vaccination, screening, testing, and treatment contribute to the uneven burden.
Veronika Fedirko, a professor of epidemiology at the University of Texas MD Anderson Cancer Center who was not involved in the study, said disparities also exist within the United States.
“Some populations have higher rates of infections such as hepatitis B, hepatitis C, HPV or H. pylori, while others have less access to vaccination, screening or treatment,” Fedirko said.
She cautioned that having a cancer-causing infection does not mean a person will develop cancer. Cancer generally develops in only a small proportion of infected people and may depend on factors including age, immune function, smoking, genetics and other exposures.
Vaccination And Treatment Can Reduce Risk
The researchers said vaccination, testing and treatment can provide opportunities to prevent infection-related cancers. HPV and hepatitis B can be prevented through vaccination, while H. pylori and hepatitis C can be identified and treated.
H. pylori can cause long-term stomach inflammation and increase the risk of gastric cancer. Treating the infection with antibiotics can reduce that risk.
HPV can cause cervical, anal, penile, vaginal, vulvar and oropharyngeal cancers. Preventing HPV infection through vaccination can therefore reduce the risk of those cancers.
Dr. Nancy Lee, a radiation oncologist at Memorial Sloan Kettering Cancer Center who was not involved in the study, said the findings reinforce the importance of vaccination.
“The public needs to be made aware, and vaccination should be reinforced,” Lee said.
Rumgay also cited safe injection practices, condom use and HIV pre-exposure prophylaxis as measures that can reduce transmission of infections linked to cancer.
“If implemented widely and equitably, these strategies could prevent hundreds of thousands, if not millions, of future cancer cases worldwide,” Rumgay said.
