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Evidence regarding the risk of cancer development after asthma diagnosis is controversial and inconclusive. This study sought to determine whether asthma is associated with an increased risk for incident cancer. Two independent, population-based, longitudinal cohorts were examined, and estimated hazard ratios were determined using Cox regression. One group consisted of an unmatched cohort of 475,197 participants and a propensity score–matched cohort of 75,307 participants from the National Health Insurance Service–National Sample Cohort (NHIS-NSC; claims-based data from 2003 to 2015). The other group consisted of 5,440 participants from the Ansan-Ansung cohort (interview-based data from 2001 to 2014). The NHIS-NSC matched cohort had 572,740 person-years of follow-up, 6,885 people with new asthma diagnoses, and 68,422 people without asthma diagnoses. Adults with asthma had a 75% greater risk of incident cancer overall. The excess risk for incident cancer was greatest during the first 2 years after asthma diagnosis, and this risk remained elevated throughout follow-up. Patients with nonatopic asthma had a greater risk of overall cancer than those with atopic asthma. A high cumulative dose of inhaled corticosteroids among asthma patients was associated with a 56% reduced risk of lung cancer, but had no effect on the risk of overall cancer. The results from the NHIS-NSC unmatched cohort and the Ansan-Ansung cohort were similar to the primary results from the NHIS-NSC matched cohort. Asthma development was associated with an increased risk of subsequent cancer in 2 different Korean cohorts. Our findings provide an improved understanding of the pathogenesis of asthma and its relationship with carcinogenesis and suggest that clinicians should be aware of the higher risk of incident cancer among patients with asthma. [ABSTRACT FROM AUTHOR]

Although the different age groups had differences in sensitivity of asthma exacerbations (AEs) to environmental factors, no comprehensive study has examined the age-stratified effects of environmental factors on AEs. We sought to examine the short-term effects in age-stratified groups (infants, preschool children, school-aged children, adults, and the elderly) of outdoor environmental factors (air pollutants, weather conditions, aeroallergens, and respiratory viral epidemics) on AEs. We performed an age-stratified analysis of the short-term effects of 4 groups of outdoor environmental factors on AEs in Seoul Metropolitan City (Korea) from 2008 and 2012. The statistical analysis used a Poisson generalized linear regression model, with a distributed lag nonlinear model for identification of lagged and nonlinear effects and convergent cross-mapping for identification of causal associations. Analysis of the total population (n = 10,233,519) indicated there were 28,824 AE events requiring admission to an emergency department during the study period. Diurnal temperature range had significant effects in pediatric (infants, preschool children, and school-aged children) and elderly (relative risk [RR], 1.056-1.078 and 1.016, respectively) subjects. Tree and weed pollen, human rhinovirus, and influenza virus had significant effects in school-aged children (RR, 1.014, 1.040, 1.042, and 1.038, respectively). Tree pollen and influenza virus had significant effects in adults (RR, 1.026 and 1.044, respectively). Outdoor air pollutants (particulate matter of ≤10 μm in diameter, nitrogen dioxide, ozone, carbon monoxide, and sulfur dioxide) had significant short-term effects in all age groups (except for carbon monoxide and sulfur dioxide in infants). These findings provide a need for the development of tailored strategies to prevent AE events in different age groups. [ABSTRACT FROM AUTHOR]