5 Common Infections Linked to Millions of Cancer Cases

A new study estimates that 2.3 million cancer cases in 2024 were linked to infectious diseases. Learn about five infections associated with cancer risk and prevention.

Cancer can develop for many different reasons, including inherited factors, lifestyle habits and environmental exposures. However, researchers continue to identify another important factor that may contribute to cancer development: infections.

A new study highlighted by researchers from the International Agency for Research on Cancer estimates that 2.3 million new cancer cases worldwide in 2024, representing about 12% of all new cases, were attributable to infectious diseases. The findings emphasize the role of infection prevention, vaccination, screening and treatment as part of broader cancer prevention efforts.

Five infections in particular were identified as contributing to a substantial number of cancer cases: Helicobacter pylori, human papillomavirus, hepatitis B, Epstein-Barr virus and hepatitis C.

Here is what the source reports about each infection and its connection to cancer.

1. Helicobacter pylori and Stomach Cancer

Helicobacter pylori, commonly known as H. pylori, was associated with an estimated 760,000 cancer cases in 2024, equivalent to about 4% of all cancer cases, according to the study.

H. pylori is a widespread bacterial infection. More than half of the world's population may become infected during their lifetime. Transmission can occur through contact with infected saliva, vomit or stool, as well as through contaminated food, water or surfaces.

Many people with H. pylori do not experience noticeable symptoms. In some cases, however, the infection can cause inflammation of the stomach lining or contribute to peptic ulcers. Possible symptoms include stomach discomfort, bloating, burping, reduced appetite and weight loss.

Long-term inflammation and substances produced by the bacteria can damage stomach cells. Over time, this damage may contribute to the development of stomach cancer.

Basic hygiene measures, including regular handwashing and consuming food prepared in clean conditions, can help reduce infection risks. People diagnosed with H. pylori should also follow their healthcare professional's recommended treatment, including completing prescribed antibiotics when appropriate.

2. Human Papillomavirus, or HPV

Human papillomavirus, commonly called HPV, was associated with approximately 750,000 new cancer cases worldwide, according to the information in the source. HPV is particularly important because it is responsible for almost all cervical cancers and is also associated with several other cancers.

HPV can be transmitted through sexual contact and other forms of intimate skin-to-skin contact. Some types of HPV can cause warts, while certain high-risk types can contribute to cellular changes that may eventually develop into cancer.

HPV is linked to cancers affecting the cervix, throat, anus, vulva, penis and vagina.

One of the major tools for prevention is HPV vaccination. The source reports that the vaccine provides protection against around 90% of HPV-related cancers. It also notes recommendations for vaccination during childhood and for eligible young adults who have not previously received the vaccine.

Safe sexual practices and appropriate cervical cancer screening can also play an important role in reducing health risks associated with HPV.

3. Hepatitis B and Liver Cancer

Hepatitis B was linked to an estimated 360,000 cancer cases in 2024, representing approximately 2% of new cancer cases, according to the study information.

Hepatitis B is a viral infection that affects the liver. While some infections are temporary, an infection that continues for more than six months can become chronic.

Chronic hepatitis B can increase the risk of serious liver complications, including cirrhosis and liver cancer.

Symptoms of an acute hepatitis B infection can include abdominal discomfort, fever, joint pain, dark urine and jaundice. However, symptoms can vary, and some infected people may not experience obvious signs.

Vaccination is an important prevention measure. The source notes that hepatitis B vaccination is recommended for infants, unvaccinated children and many adults, with additional recommendations for certain older adults who have increased risk.

4. Epstein-Barr Virus

The Epstein-Barr virus, or EBV, was associated with approximately 260,000 cancer cases in 2024, according to the study.

EBV is extremely common, with the source estimating that around 90% of people worldwide have been infected. It is best known as the primary cause of infectious mononucleosis, commonly called mono.

Symptoms of an EBV infection can include fatigue, fever, sore throat and swollen lymph nodes. Most people who encounter EBV do not develop cancer, but the virus has been associated with certain cancers.

Researchers have linked EBV to nasopharyngeal cancer, as well as some forms of lymphoma and stomach cancer.

The virus spreads mainly through bodily fluids, particularly saliva. Avoiding the sharing of drinks, food or personal items such as toothbrushes can help reduce exposure.

5. Hepatitis C

Hepatitis C was associated with approximately 160,000 cancer cases in 2024, representing less than 1% of cancer cases, according to the source.

Hepatitis C is a bloodborne virus that can cause long-term liver damage. One common route of transmission involves exposure to infected blood, including through shared needles.

Unlike hepatitis B, there is currently no vaccine for hepatitis C. However, hepatitis C can be cured with appropriate antiviral medication.

Reducing exposure to infected blood is an important prevention strategy. People should also take care when choosing tattoo and body-piercing facilities and ensure that proper safety and sterilization procedures are followed.

Infection Prevention Could Play a Role in Cancer Prevention

The study's findings highlight how preventing and treating certain infections could contribute to reducing cancer rates worldwide. Researchers specifically emphasized measures such as vaccination, screening, testing, treatment, safe injection practices and safer sexual practices.

The figures also demonstrate why awareness of infection-related cancer risks matters. Although an infection does not automatically mean that a person will develop cancer, certain persistent infections can create conditions that increase cancer risk over time.

Preventive healthcare can therefore be an important part of maintaining long-term health. Vaccination where recommended, appropriate screening, good hygiene and timely medical treatment can help reduce the risks associated with several infections discussed in the study.

Final Thoughts

Cancer has many causes, and no single factor can explain every case. The latest research nevertheless draws attention to the connection between infectious diseases and cancer development.

H. pylori, HPV, hepatitis B, Epstein-Barr virus and hepatitis C are all common infections, but their potential long-term health consequences differ significantly. Some can be prevented through vaccination, while others can be managed or cured through medical treatment.

Understanding these infections and following evidence-based prevention and screening recommendations may help reduce preventable health risks.

Disclaimer: This article is provided for general informational and educational purposes only. It is not intended to provide medical advice, diagnosis or treatment. Having one of the infections discussed above does not mean that a person will develop cancer. Individual risks vary depending on factors such as medical history, age, lifestyle and other health conditions. Always consult a qualified healthcare professional for personalized medical advice, testing, vaccination and treatment recommendations.