Increased rate of infections may indicate a future cancer diagnosis

https://www.eurekalert.org/pub_releases/2020-04/aafc-iro041520.php

News Release 17-Apr-2020
American Association for Cancer Research

Bottom Line: Patients experienced a greater occurrence of infections in the years preceding a cancer diagnosis.

Journal in Which the Study was Published: Cancer Immunology Research, a journal of the American Association for Cancer Research

Author: Shinako Inaida, PhD, a visiting researcher at the Graduate School of Medicine at Kyoto University in Japan

Background: "Cancer can develop in an inflammatory environment caused by infections, immunity disruption, exposure to chemical carcinogens, or chronic or genetic conditions," said Inaida. "An individual's immunity is thought to be a factor in the development of cancer, but additional research is needed to understand the relationship among precancerous immunity, infections, and cancer development," added Inaida. "This information may contribute to efforts to prevent or detect cancer."

Studies have suggested an increase in infections prior to the development of non-solid tumors, such as lymphoma, chronic lymphocytic leukemia, and myeloma, explained Inaida. However, fewer studies have examined infection prior to the development of solid tumors.

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Results: The authors found that individuals in the case group had experienced higher rates of infection over the six years prior to their cancer diagnoses than those in the control group over the same time period. The largest differences in annual infection prevalence rates occurred in the sixth year, which was one year prior to cancer diagnosis. During this year, the infection prevalence rates for the case group were higher than the control group by 18 percent for influenza, 46.1 percent for gastroenteritis, 232.1 percent for hepatitis, and 135.9 percent for pneumonia.

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The authors also found that certain infections appeared to have a greater association with certain cancer types. The odds of influenza infection just before cancer detection, for example, were highest for those who developed male germ cell cancers. Additionally, the odds of pneumonia were highest in those who went on to develop stomach cancer, and the odds of hepatitis infection were highest in those who developed hematologic, blood, bone, or bone marrow cancers. "Interestingly, we found that infection afflicting a specific organ did not necessarily correlate with increased risk of cancer in the same organ," noted Inaida.

Study Limitations: A limitation of the study was the lack of information about environmental exposures, lifestyles, or underlying genetic or medical conditions, which could have contributed to increased infection in addition to causing cancer. Another limitation was that information regarding infection was based solely on diagnoses recorded in the database; thus, there may be variability in diagnoses across different clinicians, and some infections may not have been diagnosed or recorded. The small sample size for rare cancers was an additional limitation.