The International Agency for Research on Cancer (IARC) has presented findings that highlight the role of infections in cancer. By 2024, infections are estimated to cause one in eight of cancer cases worldwide. This translates to 2.3 million new cases, with five main infections driving these numbers.
The study, published in the journal Lancet Oncology on September 28, emphasizes the potential to prevent cancer through improved infection control strategies. Dr. Patrick Moore of the University of Pittsburgh stated that the impact of infections on cancer is substantial. He suggests the figures might be conservative and that the actual impact could be greater. Geographical variations in specific infections are significant, as demonstrated by HIV treatment reductions in Sub-Saharan Africa potentially increasing infectious cancers. Conversely, hepatitis B virus (HBV) vaccination expansion in Asia could reduce liver cancer cases.
Professor Karl Munger from Tufts University noted that infection-associated cancers might comprise 15 to 20 percent of global cases, though less in high-income regions like the U.S. He underscores the importance of addressing infection-related cancers, especially since many are preventable.
Leading Infections Causing Cancer
The study identifies Helicobacter pylori, human papillomavirus (HPV), hepatitis B and C viruses, and Epstein–Barr virus as leading causes. Helicobacter pylori is associated with around 760,000 stomach cancer cases globally. HPV is linked to approximately 750,000 cases, including cervical, anal, vulvar, vaginal, penile, and some head and neck cancers. HBV contributed to 360,000 liver cancer cases. Epstein–Barr virus was linked to 260,000 cases, including nasopharyngeal cancer. Hepatitis C virus was responsible for 160,000 liver cancer cases.
Regions such as Eastern Asia, Sub-Saharan Africa, and Southeast Asia experience higher cancer burdens due to infections. H. pylori and HBV have a significant impact in Eastern Asia, while HPV-related cancers are more prevalent in Sub-Saharan Africa. These differences arise from varying infection prevalence, access to health services, and socio-economic factors.
Dr. Shan-Lu Liu from The Ohio State University observed that these cancer cases could be preventable through vaccinations, infection control, screening, and treatment. Geographic disparities highlight the importance of global health equity in addressing these issues.
Understanding Infection-Caused Cancer
Dr. Gary Clifford from the IARC explains that infections can disrupt normal cellular processes, leading to cancer. Some infections hijack cell machinery to replicate, increasing mutation risks. Dr. Liu adds that chronic inflammation and tissue damage also contribute to abnormal cell growth.
Dr. Moore highlights that several viruses carry oncogenes capable of directly inducing cancer under certain conditions such as immune suppression.
Preventability of Infection-Related Cancer
Findings demonstrate significant cancer prevention opportunities through addressing infections. Effective interventions include HPV and HBV vaccinations, screening, testing, and treatment of infections.
However, access to these measures is uneven, especially in lower-income regions. Barriers include financial, social, and political challenges that limit vaccination and treatment uptake.
The researchers call for policies to enhance these interventions. Necessary steps include improving vaccine availability, testing, and healthcare accessibility, particularly in regions with high infection-related cancer burden.
Dr. Liu believes expanding vaccination and enhancing screening could significantly reduce cancer cases globally.
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