It is estimated that one in every eight newly diagnosed cancer patients worldwide in 2024 had an infectious agent, such as a virus or bacterium, as the cause of their cancer. This finding is based on the latest estimates published by researchers from the International Agency for Research on Cancer (IARC), a body under the World Health Organization (WHO), in the academic journal *The Lancet Oncology*. While we commonly believe that smoking, obesity, and genetic factors are the primary causes of cancer, it has been reconfirmed that microorganisms to which we are easily exposed in daily life pose a lethal threat comparable to lung or liver cancer. In particular, with the addition of pathogens that were not previously clearly proven to be carcinogenic, it has been revealed that the scope of infection-induced cancer is much broader than we previously understood. Regardless of whether a country is high-income or low-income, infectious cancers remain a significant public health issue, and unlike HPV, which is preventable through vaccination, many infectious agents lack available treatments. In this article, we will explore which infections cause cancer and the extent of disparities between countries, outlining specific prevention strategies to protect our families’ health.
1 in 8 Cancers Worldwide Is Caused by Infections; Stomach Cancer-Inducing Bacteria Poses the Greatest Risk
1. The Scale of Notable Infectious Cancers and Their Primary Causes
Researchers conducted an analysis by cross-referencing the list of pathogens known to cause cancer with massive global cancer diagnosis records. In doing so, they did not simply count cases where cancer was caused by a specific infection but mathematically calculated the precise proportion of specific infections among all cancer cases. In addition to previously known pathogens, new combinations were included, such as the association between HIV and cervical cancer, and Merkel cell polyomavirus, which causes rare skin cancers. As a result, the number of cancer types included in the analysis increased by 16, numerically proving that the actual burden of infectious cancers is much heavier. While we commonly think of infections only in terms of symptoms like fever or cough, subtle bacteria or viruses can cleverly alter our body’s cells to induce cancer. Therefore, from a health management perspective, infectious disease prevention must be established as a core pillar of cancer prevention, not merely a hygiene issue.
According to global statistics, approximately 2.3 million new cancer cases in 2024 are estimated to be due to infectious factors. This figure alone allows for an intuitive understanding of the significant proportion that infections play in cancer development. A particularly noteworthy point is that these pathogens enter our bodies without our knowledge and slowly secrete carcinogenic substances over several years, or even decades. Based on this, researchers calculated the contribution of infections to each cancer type, revealing that a significant number of cancers originate from treatable infections. This provides a strong implication that advancements in cancer treatment technology alone have their limits, and that blocking infections must be the priority.
The scale of cancer caused by infections accounts for 12% of new cancers worldwide, and the scope has expanded with the discovery of new pathogens.
2. The Threat of Helicobacter Pylori, the Main Culprit of Stomach Cancer
The bacterium that causes the most infection-related cancers is *Helicobacter pylori*, which is associated with approximately 760,000 cancer cases worldwide. This bacterium is a malignant presence that increases the risk of developing stomach cancer, which is more aggressive than colorectal cancer, by causing inflammation rather than simply cooling the walls of the gastrointestinal tract. Incidence rates are highest in the East Asian region, with the burden being particularly heavy in cultural spheres where rice is a staple food, such as South Korea, Japan, and China. Infections often occur in childhood through dirty tableware or communal living environments, so if a parent is infected in a household, there is a high likelihood that children will also be exposed. This bacterium is mostly asymptomatic and difficult to detect, but if left untreated, it can lead not only to stomach ulcers but also to malignant tumors, so caution is required.
If there is a history of stomach cancer in your family or if you feel a decline in gastrointestinal function, such as indigestion, it is necessary to consider *Helicobacter pylori* testing to rule out the possibility. Current medical technology allows for the detection of this bacterium through relatively simple methods such as breath tests, blood tests, or stool tests. If diagnosed positive, it can be effectively treated with a two-week course of combined antibiotics, and early detection can significantly improve survival rates and quality of life. Therefore, including gastroscopy or *Helicobacter pylori* antibody tests in regular health check-ups is a wise choice. These small efforts are essential to protect our families from preventable bacterial cancers.
*Helicobacter pylori* is the leading cause of infectious stomach cancer worldwide, posing a particular problem in the East Asian region.
3. HPV Vaccines and Strategies for Eradicating Cervical Cancer
Cancers caused by the Human Papillomavirus (HPV) number approximately 750,000 worldwide, with particularly high incidence rates observed in sub-Saharan Africa. HPV is a virus with a proven strong causal relationship, responsible for 100% of cervical cancer cases, and it also broadly attacks anal cancer, vaginal cancer, penile cancer, and some head and neck cancers. The only complete preventive measure we know of is the vaccine, and due to its sexually transmitted nature, vaccination before reaching adulthood is most effective. Looking at the case of Canada, cervical cancer incidence rates have steadily decreased thanks to childhood vaccination programs, but recently, the rate of decline has plateaued. Experts warn that if vaccination rates are not maintained at 90% and timely follow-up care after screening is not provided, achieving future goals for cervical cancer eradication will become very difficult.
In many countries, including South Korea, the HPV vaccine is included in the national mandatory vaccination program, but this suggests that continuous campaigns are still needed to increase vaccination rates. In particular, there is a need to educate both adult women and men in their early 20s to 30s on the importance of the vaccine. Vaccination has a miraculous effect of preventing the virus infection itself, bringing the cancer incidence rate close to zero. However, for those who are already infected or are older, the best course of action is to detect even minor changes early through regular Pap smears or HPV DNA tests. Since survival rates vary greatly depending on the stage of detection, we must achieve both prevention and screening.
To eradicate HPV-related cervical cancer, high vaccination rates, regular screening, and timely follow-up care must be linked.
4. Regional Disparities and Inadequate Infection Management
The burden of infectious cancers is distributed very unequally worldwide, stemming from historically accumulated disparities in medical infrastructure. High-income countries have systematically built cancer screening programs and extensive vaccination systems over the past few decades, whereas low-income countries still lack basic access to healthcare. Even with exposure to the same pathogen, differences in the quality of diagnosis and treatment significantly alter the likelihood of progression to cancer. For example, when infected with Hepatitis B or C, patients in North America and Europe can undergo regular liver function monitoring and antiviral treatment when necessary to prevent cancer progression, whereas this is often not the case in developing countries. These structural issues are difficult to resolve through individual effort alone, and it is urgent for public medical systems to cooperate internationally to distribute vaccines and screening kits to low-income areas.
Even within Canada, regional differences are apparent, with some provinces reaching vaccination rates close to 90%, while others remain at around 66%. This can be seen as a result of the combined effects of medical information asymmetry and the absence of community campaigns. Furthermore, since some infectious cancers can lead to fatal outcomes if neglected, region-specific prevention policies must be implemented. Additionally, in areas with high immigrant populations, targeted screening considering the high-risk characteristics of their countries of origin (e.g., stomach cancer in East Asians, cervical cancer in Latin Americans) is proposed. Only when resources are concentrated from areas where healthcare is lacking to where it is needed can we gain the upper hand in the war against infectious cancers.
National disparities in infectious cancer incidence stem from differences in healthcare access and prevention systems, necessitating international cooperation.
5. EBV and the Problem of Lack of Treatments
The Epstein-Barr Virus (EBV) has had its importance further highlighted in this study compared to the past. EBV can cause rare but malignant cancers such as nasopharyngeal cancer, some types of stomach cancer, and Hodgkin lymphoma, and is linked to approximately 260,000 cancer cases worldwide. Previous estimates underestimated the proportion attributed to EBV, but the latest analysis confirmed that its disease burden is considerably larger. More dangerously, there is currently no effective vaccine or antibiotic to prevent infection with this virus. With relationships with chronic diseases, such as multiple sclerosis, gradually being elucidated, research on developing an EBV prevention vaccine is expected to accelerate in the future.
EBV is mostly transmitted through saliva or mosquitoes in childhood, and if infected during childhood, the immune system often adapts, leaving the individual asymptomatic. However, when becoming an adult or when immunity is weakened, it can reactivate and possess the toxicity to aid in the growth of cancer cells. Unlike *Helicobacter pylori* or HPV, there is no simple antibiotic treatment for EBV, so maintaining immunity is the most realistic line of defense. Maintaining our body’s defense system in optimal condition through stress management, sufficient sleep, and a balanced diet is the way to protect ourselves from EBV. It is expected that the development of an EBV vaccine in the future will bring revolutionary changes to cancer prevention.
EBV can cause cancer, but the lack of a therapeutic vaccine makes the development of new treatments urgent.
6. Practical Guidelines for Residents of South Korea
Since most infectious cancers are preventable, the most certain measures we can take are improving lifestyle habits and undergoing regular check-ups. Using personal tableware, washing hands, and eating cooked food are the first steps in preventing *Helicobacter pylori* infection. In terms of sexual practices, using condoms safely helps reduce the risk of HPV and HIV infection. Additionally, the Hepatitis B vaccine is the most powerful weapon against preventable liver cancer, so if a mother is a Hepatitis B virus carrier, the newborn must be vaccinated. If there is a history of infection with hepatitis pathogens, it is important to regularly check for liver cirrhosis or early signs of cancer through periodic ultrasound examinations, and those with underlying liver diseases should pay particular attention.
South Korea has well-established medical infrastructure with high access to screening, so we should actively utilize this environment. From the mid-50s onwards, carefully review the cancer history of immediate family members, and if there is such a family history, increase the frequency of screening specialized for that type of cancer. Rather than relying solely on hospitals, it is necessary to develop one’s own prevention routine by checking the preparation process of one’s food and the hygiene of the surrounding environment. Health can deteriorate at any moment if neglected, but the defensive barrier thickens with a little care. Please take time today to organize the monthly screening items with your family and check on necessary vaccinations.
Active self-management and screening plans based on medical knowledge lead to immediate risk reduction.
Hygiene management, and regular professional medical check-ups are the three pillars of infectious cancer prevention.
Frequently Asked Questions
=