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. 2025 Mar 24:82:103152.
doi: 10.1016/j.eclinm.2025.103152. eCollection 2025 Apr.

Association between socioeconomic position and lung cancer incidence in 16 countries: a prospective cohort consortium study

Justina Ucheojor Onwuka  1 , Hana Zahed  1 , Xiaoshuang Feng  1 , Karine Alcala  1 , Loretta Erhunmwunsee  2 , Randi M Williams  3 , Melinda C Aldrich  4 , Jasjit S Ahluwalia  5 , Demetrius Albanes  6 , Alan A Arslan  7 , Julie K Bassett  8   9 , Paul Brennan  1 , Qiuyin Cai  10 , Chu Chen  11 , Niki Dimou  12 , Pietro Ferrari  12 , Neal D Freedman  6 , Wen-Yi Huang  6 , Michael E Jones  13 , Miranda R Jones  14 , Rudolf Kaaks  15 , Woon-Puay Koh  16   17 , Arnulf Langhammer  18   19 , Linda M Liao  6 , Reza Malekzadeh  20 , Roger L Milne  8   9   21 , Thomas E Rohan  22 , Maria-José Sánchez  23   24   25 , Mahdi Sheikh  1 , Rashmi Sinha  6 , Xiao-Ou Shu  10 , Victoria L Stevens  26 , Lesley F Tinker  27 , Kala Visvanathan  28   29 , Ying Wang  30 , Renwei Wang  31 , Stephanie J Weinstein  6 , Emily White  32 , Jian-Min Yuan  33   34 , Wei Zheng  35 , Mattias Johansson  1 , Hilary A Robbins  1
Affiliations

Association between socioeconomic position and lung cancer incidence in 16 countries: a prospective cohort consortium study

Justina Ucheojor Onwuka et al. EClinicalMedicine. .

Abstract

Background: Studies have reported higher lung cancer incidence among groups with lower socioeconomic position (SEP). However, it is not known how this difference in lung cancer incidence between SEP groups varies across different geographical settings. Furthermore, most prior studies that assessed the association between SEP and lung cancer incidence were conducted without detailed adjustment for smoking. Therefore, we aimed to assess this relationship across world regions.

Methods: In this international prospective cohort consortium study, we used data from the Lung Cancer Cohort Consortium (LC3), which includes 20 prospective population cohorts from 16 countries in North America, Europe, Asia, and Australia. Participants were enrolled between 1985 and 2010 and followed for cancer outcomes using registry linkages and/or active follow-up. We estimated hazard ratios (HRs) for the association between educational level (our primary measure of SEP, in 4 categories) and incident lung cancer using Cox proportional hazards models separately for participants with and without a smoking history. The models were adjusted for age, sex, cohort (when multiple cohorts were included), smoking duration, cigarettes per day, and time since cessation.

Findings: Among 2,487,511 participants, 53,830 developed lung cancer during a 13.5-year median follow-up (IQR = 6.5-15.0 years). Among participants with a smoking history, higher education was associated with decreased lung cancer incidence in nearly every cohort after detailed smoking adjustment. By world region, this association was observed in North America (HR per one-category increase in education [HRtrend] = 0.88, 95% CI = 0.87-0.89), Europe (HRtrend = 0.89, 95% CI = 0.88-0.91), and Asia (HRtrend = 0.91, 95% CI = 0.86-0.96), but not in the Australian study (HRtrend = 1.02, 95% CI = 0.95-1.09). By histological subtype, education associated most strongly with squamous cell carcinoma and more weakly with adenocarcinoma (p-heterogeneity < 0.0001). Among participants who never smoked, there was no association between education and lung cancer incidence in any cohort (all p-trend > 0.05), except the USA Southern Community Cohort Study (HRtrend = 0.75, 95% CI = 0.62-0.90).

Interpretation: Based on longitudinal data from 2.5 million participants from 16 countries, our findings suggest that higher educational attainment was associated with lower lung cancer risk among participants with a smoking history, but not among participants who never smoked. Limitations of our study include that cohort participants cannot fully represent the general populations of the geographical regions included, and education was the only measure of SEP consistently available across our consortium.

Funding: This study was supported in part by the National Cancer Institute (NCI), the Lung Cancer Research Foundation (LCRF), and the World Cancer Research Fund (WCRF).

Keywords: Geographical differences; Incidence; Lung cancer; Socioeconomic position.

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Conflict of interest statement

LE reports payments made to institution: National Cancer Institute; Lung Cancer Research Foundation; American Association of Thoracic Surgery; honoraria for giving grand rounds: UC Davis Health; honoraria for giving keynote address: Lung Cancer Health Equity Symposium; participation on a Data Safety Monitoring Board or Advisory Board (No payments): Lung Cancer Research Foundation, Bristol Myer Squibb Foundation; advisory board participation: PCORI research grant. RW reports grants from the US National Cancer Institute (R00CA256515, R01CA274716). MCA reports participation in the National Lung Cancer Roundtable (service on the Health Equity Task Group and the Lung Cancer Early Detection Implementation Strategies Task Group), and is a member of the scientific steering committee of Guardant Health. JSA reports funding from the National Institute of General Medical Sciences (NIGMS), National Cancer Institute (R01 CA282223, R01CA25925, R01CA298165), National Institute on Minority Health and Health Disparities (5R01MD017302), National Institute of Drug Abuse (1R01DA055999); consulting fees, equity, and Scientific Advisory Board chairmanship from Onovia, a start-up company working on a prescription nicotine replacement product; receipt of funds for travel expenses (no honoraria) as a speaker for the annual GTNF conferences from 2021 to 2024, the 2022 and 2024 Tobacco Science Research Conference, the 2024 Coresta annual scientific conference, and the 2021–2024 annual Food and Drug Law Institute annual scientific conferences; Board of Directors membership for the Council of Tobacco Treatment Training Programs. J-MY reports NIH/NCI grants (R01CA155809 and R01CA269223) to his institution. All other authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Association between lung cancer incidence and educational level among Lung Cancer Cohort Consortium participants with and without a history of smoking in Europe, North America, Asia, and Australia. Footnote: Hazard ratios (HRs) are shown with adjustment for: ∗age, sex, and cohort (with and without history of smoking) and †age, sex, smoking duration, cigarettes per day, time since cessation, and cohort (with history of smoking). Some confidence intervals extend outside of the plot area. Pooled in each region: Europe (ATBC (Finland), EPIC (Denmark), EPIC (Germany), EPIC (Italy), EPIC (Norway), EPIC (Spain), EPIC (Sweden), EPIC (Netherlands), EPIC (UK), GS (UK), UK Biobank (UK), HUNT (Norway)); Australia (MCCS); North America (CPSII (USA), NYUWHS (USA), PLCO (USA), SCCS (USA), VITAL (USA), WHI (USA), AARP (USA), CLUE (USA)), CSDLH (Canada); Asia (SCHS (Singapore), SCS (China), SMHS (China), Golestan (Iran)). The SWHS (China) was excluded because results differed from those in other cohorts (see later figures).
Fig. 2
Fig. 2
Association between lung cancer incidence and educational level among Lung Cancer Cohort Consortium participants with a history of smoking. Footnote: Educational level is modeled as an ordinal variable in 4 categories. Hazard ratios (HRs) are shown without adjustment (for single cohort analyses) or with adjustment for cohort only (for pooled analyses) [in blue], with adjustment for age, sex, smoking status, and (for pooled analyses) cohort [in red], and with adjustment for age, sex, smoking duration, cigarettes per day, time since cessation, and (for pooled analyses) cohort [in purple]. Some confidence intervals extend outside of the plot area.
Fig. 3
Fig. 3
Association between lung cancer incidence and educational level among Lung Cancer Cohort Consortium participants without a history of smoking. Footnote: Educational level is modeled as an ordinal variable in 4 categories. Hazard ratios (HRs) are shown without adjustment (for single cohort analyses) or with adjustment for cohort only (for pooled analyses) [in blue], and with adjustment for age, sex, and (for pooled analyses) cohort [red]. Some confidence intervals extend outside of the plot area.
Fig. 4
Fig. 4
Association between lung cancer incidence and educational level by stage and histological subtype among Lung Cancer Cohort Consortium participants with and without history of smoking. Footnote: Educational level is modeled as an ordinal variable in 4 categories. Hazard ratios (HRs) are shown for histological subtypes [adenocarcinoma (blue), small cell (red) and squamous cell (purple)] and stage at diagnosis [Stage I-II (blue) and Stage III-IV (red)]. Models are adjusted minimally for age, sex, and cohort; and for age, sex, smoking duration, cigarettes per day, time since cessation, and cohort. p-het: p-heterogeneity for model adjusted for age, sex, smoking duration, cigarettes per day, time since cessation, and cohort. We pooled all cohorts (19% and 24% missing and other histology respectively and 66% missing stage), except Golestan (Iran, 100% missing stage and histology) and CSDLH (Canada, 100% missing stage and 14% missing histology). We used a competing risk analysis which considers each histology/stage category of interest by treating outcomes of the other histology/stage categories as censored observations.
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