Abstract 1950: Socioeconomic status and lung cancer incidence: An analysis of data from 15 countries in the Lung Cancer Cohort Consortium
Authors: Onwuka Justina U. , Zahed Hana , Feng Xiaoshuang , Alcala Karine , Johansson Mattias , Robbins Hilary A. , Consortium Lung Cancer Cohort 
Published: April 2023

Abstract
Background: Lung cancer is the leading cause of cancer death worldwide. We explored the relationship between socioeconomic status and lung cancer incidence across world regions, using educational level as a proxy for socioeconomic status.
Methods: We analyzed the harmonized database of the Lung Cancer Cohort Consortium (LC3). The current study included data from 18 prospective cohorts from 15 countries in the US, Europe, Asia, and Australia. Separately for participants who never or currently/formerly smoked, we estimated the association between educational level and incident lung cancer using Cox proportional hazards models. Information on education was harmonized using the International Standard Classification of Education and then modeled as an ordinal variable in 4 categories. Models were adjusted for age, sex, and for participants who currently/formerly smoked, smoking duration, cigarettes per day, and time since cessation.
Results: Among 2.6 million participants from 15 countries, 62,645 developed lung cancer during follow-up (median follow-up = 12.6 years). Among current/former smokers, increased educational level was associated with decreased lung cancer incidence in most cohorts after adjustment for age, sex, and detailed smoking information, with HRs ranging from 0.77 (95%CI: 0.42-1.41) per 1-unit increase in educational level in the Iranian Golestan Cohort Study to 1.02 (95%CI: 0.95-1.09) in the Australian Melbourne Collaborative Cohort Study. When grouping by world region, the association between education and lung cancer incidence among currently/formerly smoking participants was similar for the US (HRpooled=0.88, 95%CI: 0.87-0.89), Europe (HRpooled=0.89, 95%CI: 0.88-0.91), and Asia (HRpooled=0.91, 95%CI: 0.86-0.96), but attenuated in the Australian cohort (HR=1.02, 95%CI: 0.95-1.09). Among never smokers, after adjustment for age and sex, there was no statistically significant association between educational level and lung cancer incidence (p-trend&gt;0.05 in all cohorts), with the exception of the US Southern Community Cohort Study, which comprises primarily African-Americans and showed a HR of 0.75 (95%CI: 0.62-0.90).
Conclusion: Among currently and formerly smoking individuals, higher educational level showed a strikingly consistent decreased risk of incident lung cancer across cohorts from 4 continents, after detailed adjustment for smoking. In contrast, among people who never smoked, there was no association between education and lung cancer incidence in any cohort, with the exception of the Southern Community Cohort Study. Further research is needed to clarify the mechanisms, either related or unrelated to smoking, that contribute to the association between education and lung cancer risk.
Citation Format: Justina U. Onwuka, Hana Zahed, Xiaoshuang Feng, Karine Alcala, Mattias Johansson, Hilary A. Robbins, Lung Cancer Cohort Consortium. Socioeconomic status and lung cancer incidence: An analysis of data from 15 countries in the Lung Cancer Cohort Consortium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1950.