Infectious Agents Linked to One‑Eighth of Global Cancer Cases in 2024, Study Finds

A global analysis published in The Lancet Oncology, led by researchers at the International Agency for Research on Cancer (IARC), found that roughly one in eight new cancer cases worldwide in 2024—about 2.3 million—were linked to infectious agents. The two leading contributors were Helicobacter pylori and human papillomavirus (HPV), with hepatitis B also playing a significant role. All three infections can often be prevented or treated well before cancer develops.

A Global Estimate with a Household Message

The IARC study estimated that in 2024, H. pylori was responsible for roughly 760,000 cancer cases, HPV for about 750,000, and hepatitis B for around 360,000. Epstein‑Barr virus contributed to approximately 260,000 cases, while hepatitis C accounted for about 160,000. Eastern Asia bore the highest burden, representing 42 % of all infection‑related cancers, driven primarily by H. pylori and hepatitis B. This analysis is the first global estimate of its kind to incorporate HIV.

“Infectious agents are a major preventable cause of cancer globally,” said lead author Harriet Rumgay, PhD, of IARC’s Cancer Surveillance Branch, and colleagues. The authors highlighted that inequities particularly affect low‑ and middle‑income nations, even though vaccines, tests, and treatments exist for many of these infections.

Vaccines That Target Cancer‑Causing Viruses

HPV causes approximately 36,000 cancers each year in the United States, including cervical, oropharyngeal, and anal cancers. The CDC recommends a two‑dose series administered at ages 11–12, with vaccination possible as early as age 9. Teens and young adults who start the series between ages 15 and 26 require three doses. While routine vaccination is not advised for all individuals aged 27–45, some adults in this age group may elect to be vaccinated after discussing options with their clinician.

On January 5, 2025, the CDC released a new childhood immunization schedule that reduced the HPV regimen to a single dose and removed universal hepatitis B recommendations for children. A federal court in Massachusetts stayed those changes on March 16, effectively restoring the prior 2025 schedule. The government has appealed the decision, and the American Academy of Pediatrics continues to endorse routine HPV and hepatitis B vaccination.

Hepatitis B can silently damage the liver for decades before progressing to liver cancer. Under the reinstated schedule, infants receive a birth dose and complete a series; unvaccinated children and adolescents are caught up; adults aged 19–59 are recommended for vaccination, and adults 60 years and older with risk factors are also advised to vaccinate, with optional vaccination for others.

“Vaccinate and treat our way out of millions of future cancer diagnoses,” said David Greenberg, MD, a hematologist‑oncologist at Hackensack Meridian Health in New Jersey, reflecting a clinician’s perspective rather than a study result.

The Stomach Infection Many Adults Never Test For

Helicobacter pylori infection is often asymptomatic but can lead to ulcers and, in a minority of individuals, gastric cancer. In North America, an estimated 30 %–40 % of adults carry the bacterium. The American College of Gastroenterology’s 2024 guideline recommends testing for patients with current or prior ulcers, household contacts of a confirmed case, individuals with a family history of gastric cancer, and immigrants from regions where H. pylori and gastric cancer are common. Testing methods typically include breath tests, stool antigen assays, or endoscopic biopsies. Positive cases are usually treated with a combination of antibiotics and acid‑suppressing medication, followed by a repeat test at least four weeks later to confirm eradication, as treatment may need to be repeated.

Costs, Coverage and the Limits of the Data

Most recommended vaccines are covered by insurance plans, and eligible children can receive them at no cost through the federal Vaccines for Children program. Uninsured adults may obtain low‑cost vaccines and hepatitis B screenings through local health departments or community health centers. Coverage for H. pylori testing generally depends on documented symptoms or risk factors; patients are advised to inquire about costs before testing. The modeling approach used in the study does not alter existing U.S. guidelines. Families uncertain about a child’s immunization status can verify records with their pediatrician or state immunization registry. Adults experiencing persistent indigestion, black or bloody stools, unexplained weight loss, or recurrent vomiting should seek prompt medical evaluation rather than waiting for routine screening. While the majority of infection‑related cancers occur globally, the preventive tools—vaccines, screening, and treatment—are readily accessible in the United States.

Key Questions Answered

What did the new study find? The study estimated that about 2.3 million new cancer cases worldwide in 2024—approximately one in eight—were attributable to infections, with H. pylori and HPV being the leading causes, followed by hepatitis B.

Who should get the HPV vaccine? The CDC recommends a two‑dose series at ages 11–12 (starting as early as age 9). Individuals through age 26 who missed vaccination should catch up, and select adults aged 27–45 may consider vaccination after discussing options with a health‑care provider.

Who needs hepatitis B vaccination? Under the reinstated federal schedule, vaccination is recommended for all infants, unvaccinated children and adolescents, and adults aged 19–59. Adults 60 years and older with risk factors are also advised to vaccinate, while others in this age group may opt for vaccination after counseling.

When should someone ask about H. pylori testing? Testing is advised for persons with current or past ulcers, household contacts of a positive case, individuals with a family history of gastric cancer, and immigrants from high‑prevalence regions.

Does having one of these infections mean cancer is likely? No. The majority of people infected with HPV, hepatitis B, or H. pylori never develop cancer. Vaccination, screening, and treatment further lower the risk.

Are federal vaccine recommendations changing? A January 2026 revision to the CDC immunization schedule that would have reduced the HPV regimen to a single dose and omitted universal hepatitis B recommendations was stayed by a federal court in March 2025, restoring the prior schedule. The government has appealed the decision. Families should confirm current guidance with their pediatrician or local health department.

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