Infections caused 13% of cancers in 2018
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In 2018, infections were the cause of 13% of all new cancer diagnoses, totaling 2.2 million new cases worldwide, although these totals do not include nonmelanoma skin cancers, according to findings published in The Lancet Global Health.
Helicobacter pylori , HPV, hepatitis B virus and hepatitis C virus were the primary causes of these cancers, according to the researchers.
Catherine de Martel, MD, of the Infections and Cancer Epidemiology Group in France, and colleagues emphasized that these estimates are a ‘snapshot’ of the global cancer burden attributable to infections and that it is not possible to compare previous results because of “changes in data sources, notably for cancer incidence estimates, as well as other methodological modifications.”
In addition, the overall fraction of 13% of all cancers attributed to infection “is not easily comparable with previous estimates of 18% for 2002, 16% for 2008 and 15% for 2012 and should not be interpreted as a decrease in incidence of infection-attributable cancer,” they wrote.
Using the GLOBOCAN 2018 database of cancer incidence and mortality rates, the researchers determined the absolute numbers and age-standardized incidence rates (ASIR) of infection-attributable cancers at country level. Estimates were categorized according to sex, age group and country.
They then combined that data “into geographical regions and World Bank income groups” to determine the subregional, regional and global burdens of infection-attributable cancers.
The 2.2 million infection-attributable cancer cases diagnosed around the world in 2018 corresponded to an infection-attributable ASIR of 25 cases per 100,000 person-years. Among the primary cancer-causing infections, there were 810,000 cases of H. pylori with an ASIR of 8.7 per 100,000 person-years; 690,000 cases of HPV with an ASIR of 8; 360,000 cases of HBV with an ASIR of 4.1; and 160,000 cases of HCV with an ASIR of 1.7.
At 37.9 cases per 100,000 person-years, eastern Asia had the highest rates of infection-attributable ASIR, closely followed by sub-Saharan Africa, which has an ASIR of 33.1. Northern Europe and western Asia had the lowest rates of infection-attributable ASIR at 13.6 and 13.8, respectively.
A third of the worldwide cancer cases attributable to infection occurred in China, which was driven by H. pylori and HBV. In that country, the infections have a high ASIR: 15.6 for H. pylori and 11.7 for HBV.
The HPV-related cancer burden had the clearest relationship with country income level, according to deMartel and colleagues. Specifically, in high-income countries, the ASIR for HPV is 6.9 cases compared with 16.1 cases in low-income countries.
“Estimating the burden of cancer attributable to infection could help to raise awareness and inform recommendations for action, particularly because global cancer prevention is currently seen in the context of noncommunicable diseases,” the authors wrote. “It could also help to prioritize resources and monitor the long-term success of health policies, [such as] the WHO goals of elimination of hepatitis and cervical cancer.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Paul A. Volberding, MD
A causal relationship between certain infections and human cancers is not a new concept, but there is a sense that it may explain even more cancer types as we learn more. Understanding these linkages is important because it may enable more efficient decisions on allocation of diagnostic and treatment resources, especially in low-income countries. Because some of the most important infections leading to cancers can be prevented by vaccines (eg, HPV and HBV) or antibiotics (eg, H. pylori), better information may allow more effective prevention efforts. As this paper points out, the surprisingly wide variation in the prevalence of cancer-associated infections and rates of cancers in body sites should help generate policies quite specific to each region. The authors, using a host of new information sources, have assembled an impressive summary of these issues.
The results may be surprising to many. China alone was the site of approximately 35% of infection-associated cancers, of which H. pylori (gastric cancer) and HBV (liver cancer) predominated. In sub-Saharan Africa, HPV-associated cervical cancer and human herpesvirus 8-associated Kaposi's sarcoma were notably common. The authors point out that global cancer is typically thought of as a noncommunicable disease, whereas the actually strong relationship to infections must always be considered. Infectious disease specialist must be at the table as diagnosis, treatment and prevention efforts are being designed. Once again, we are reminded of the increasingly recognized power of "big data!”
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