External Airborne-agent Exposure Increase Risk of Digestive Tract Cancer

Abstract

previous studies have suggested that in addition to respiratory system cancers, exposure to external airborne agents (EAAs) may also affect the risk of digestive tract cancer. However, previous epidemiological studies have been limited. To clarify this relationship, we conducted a Workers' Korea National Health Insurance Service cohort study. The EAA exposure group comprised participants who had ever visited a hospital as an inpatient for 'lung diseases due to external agents'. The reference population comprised men from the general working population. The EAA exposure group and reference group included a total of 98,666 and 79,959,286 person-years, respectively. Age-adjusted standardized incident rates (SIRs) with 95% confidence intervals (95%CI) were calculated for each 5-year age stratum. The SIR (95% CI) of EAA exposure was 1.30 (1.19-1.38) for all digestive tract cancers. The highest risk associated with eAA exposure was observed for oral cancer, followed by esophageal and stomach cancers [SIRs (95%CI): 3.96 (3.02-4.78), 3.47(2.60-4.25), and 1.34(1.17-1.47), respectively.] These statistically significant associations did not be attenuated in a subgroup analysis using logistic regression adjusted for age, smoking and alcohol consumption. Our findings suggest that EAA exposure should address risk reduction of both digestive tract and respiratory system cancers. Previous studies of the human health effects of external airborne agent (EAA) which were included aerosol, gas, vapor, mist, fume, dust, or smoke exposure have focused on the respiratory system 1-3 , given the assumption that such exposure primarily causes respiratory system disease. Although EAA exposure mainly occurs via the respiratory system, humans face other possible sites of exposure, namely the digestive system. The digestive system may be exposed to EAAs via several inhalation and ingestion mechanisms. First, agents filtered in the nose or exhaled from the upper respiratory tract may be swallowed 4. Second,, reduced sphincter tone around the esophageal orifice could directly allow the accidental swallowing of EAAs 5. Third, food, skin, or clothing may be contaminated by EAAs 4. Finally, an intuitive approach reveals that the origins of the gastrointestinal tract and respiratory system occur in shared structures, such as the oral cavity and pharynx. In summary, these mechanisms identify the gastrointestinal tract as a potential site of EAA exposure, with the potential for inflammatory, immunologic, or even oncogenic responses similar to those observed in the respiratory system 6. To date, little is known about the relationship between EAA exposure and the risk of digestive tract cancers. Notably, a previous well-designed cohort study found that esophageal and stomach cancer were more closely correlated with EAA exposure when compared with lung cancer, although the authors did not control for alcohol consumption 7. Nevertheless, these results encouraged subsequent epidemiological studies. Although later research also demonstrated the effects of E...

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