Long‐term exposure to air pollution and risk of n on‐Hodgkin lymphoma in Denmark: A population‐based case–control study

• Published in: International journal of cancer 2020-10, Vol.147 (7), p.1874-1880
• Main Authors: Taj, Tahir, Poulsen, Aslak H., Ketzel, Matthias, Geels, Camilla, Brandt, Jørgen, Christensen, Jesper H., Puett, Robin, Hvidtfeldt, Ulla A., Sørensen, Mette, Raaschou‐Nielsen, Ole
• Format: Article
• Language: English
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.32978

There is limited evidence regarding a possible association between exposure to ambient air pollutants and the risk of non‐Hodgkin lymphoma (NHL). Previous epidemiological studies have relied on crude estimations for air pollution exposure and/or small numbers of NHL cases. The objective of our study was to analyze this association based on air pollution modeled at the address level and NHL cases identified from the nationwide Danish Cancer Registry. We identified 20,874 incident NHL cases diagnosed between 1989 and 2014 and randomly selected 41,749 controls matched on age and gender among the entire Danish population. We used conditional logistic regression to estimate odds ratios (ORs) and adjusted for individual and neighborhood level sociodemographic variables. There was no association between exposure to PM 2.5 , BC, O 3 , SO 2 or NO 2 and overall risk of NHL but several air pollutants were associated with higher risk of follicular lymphoma, but statistically insignificant, for example, PM 2.5 (OR = 1.15 per 5 μg/m 3 ; 95% CI: 0.98–1.34) and lower risk for diffuse large B‐cell lymphoma (OR = 0.92 per 5 μg/m 3 ; 95% CI: 0.82–1.03). In this population‐based study, we did not observe any convincing evidence of a higher overall risk for NHL with higher exposure to ambient air pollutants. What's new? Known risk factors of non‐Hodgkin lymphoma (NHL) appear to be involved in only a small percentage of NHL cases. However, while other factors are suspected of influencing NHL risk, including socioeconomic factors and outdoor air pollution, existing evidence is inconclusive. In this investigation of outdoor air pollution and NHL risk in NHL patients diagnosed between 1989 and 2014 in Denmark, no association was detected between long‐term air pollution exposure at an individual's residence and overall NHL risk. Air pollution was insignificantly associated with increased risk of follicular lymphoma and reduced risk of diffuse large B‐cell lymphoma, two common NHL subtypes.