Do you know that infections are the leading cause of cancer? Cancer, as we all know, has become a very common health issue, with millions of new cases springing up every day globally.
According to a new study published in the journal The Lancet Oncology, about 1 in 8 cancer cases around the world may be linked to infections, many of which can be prevented through vaccines, screening, or straightforward treatments.
The study also found that about 2.3 million new cancer cases were attributable to infections globally in 2024, which is equivalent to 12% of all cancer diagnoses.
The five leading infections were human papillomavirus (HPV), Helicobacter pylori, hepatitis B, Epstein-Barr virus (EBV), and hepatitis C.
1. Human papillomavirus (HPV)
Human papillomavirus (HPV) is a common sexually transmitted infection spread through intimate skin-to-skin contact, including vaginal, anal, or oral sex. It can spread even when an infected person has no visible signs or symptoms.
Condoms can reduce the risk of transmission but do not provide complete protection because HPV can infect areas of skin that are not covered by a condom.
According to the International Agency for Research on Cancer (IARC), HPV was responsible for approximately 750,000 cancer cases globally in 2024, making it one of the world’s leading infection-related causes of cancer. About 600,000 of these cases were cervical cancers.
Vaccination is one of the most effective ways to prevent HPV-related cancers, while regular cervical cancer screening and checkups remain important.
2. Helicobacter pylori (H.pylori)
Helicobacter pylori, commonly called H. pylori, is a bacterium that infects the stomach.
H. pylori is a bacterial infection that infects the stomach and is a major cause of stomach issues such as ulcers and gastritis. It is usually spread through saliva, vomit, or stool.
Chronic H. pylori infection can lead to inflammation and damage the stomach lining, increasing the risk of stomach (gastric) cancer. It is also associated with a type of lymphoma called MALT lymphoma.
760,000 new cancer cases in 2024 were attributable to H. pylori, according to IARC, making it the largest infection-related cause of cancer globally. Most of these cancers were stomach cancers.
H. pylori infection can be treated with antibiotics, which can significantly reduce the risk of stomach cancer.
3. Hepatitis B Virus (HBV)
Hepatitis B (HBV) is a virus that infects the liver and, if infection becomes chronic, it can cause inflammation and damage that may eventually lead to cirrhosis or liver cancer. It usually spreads when a person comes into contact with infected blood or certain body fluids.
The latest IARC analysis estimates that HBV was responsible for approximately 360,000 cases of liver cancer globally in 2024.
Because hepatitis B often causes no symptoms, infected people may not know they have it; therefore, vaccination offers the best protection.
4. Epstein-Barr Virus (EBV)
Epstein-Barr virus (EBV) is a common virus estimated to infect about 95% of the world’s population and usually causes no serious long-term problems.
While most people infected with EBV never develop cancer, the virus is associated with several cancers, including Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, and most recently stomach cancers.
IARC’s latest estimates put the number of EBV-attributable cancer cases at approximately 260,000 worldwide in 2024, making it the fourth-largest infectious cause of cancer globally.
There is currently no licensed vaccine for the treatment of EBV.
5. Hepatitis C (HCV)
Similar to Hepatitis B, Hepatitis C (HCV) is a virus that primarily attacks the liver. If untreated, chronic hepatitis C can cause liver inflammation, fibrosis, and cirrhosis, leading to an increase in the risk of liver cancer. HCV is also associated with some cases of non-Hodgkin lymphoma.
IARC estimates that approximately 160,000 new cancer cases globally in 2024 were attributable to hepatitis C.
Unlike hepatitis B, there is currently no vaccine for hepatitis C. However, a short course of antiviral drugs can cure more than 95% of infections and substantially reduce people’s risk of developing liver cancer.