Epidemiology and Prevention - Effect Modification by Cofactors in the Impact of Body Mass Index Change on the Risk of Lung Cancer

Sep 22, 2026

Baseline body mass index (BMI) is inversely linked to lung cancer risk, but how BMI change influences that risk remains insufficiently defined. Cancer-free participants were examined in 2010 and 2014, with follow-up through 2021. BMI change categories were analyzed using competing-risk models with Fine–Gray adjustments. Persistent obesity and transitions from normal BMI to obesity reduced risk, with stronger effects in men and ever smokers.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Introduction

Background and rationale

Methods

Sourcing data from the national database

Analytical approach

Cancer Science ORIGINAL ARTICLE OPEN ACCESS Epidemiology and Prevention Effect Modification by Cofactors in the Impact of Body Mass Index Change on the Risk of Lung Cancer Su Youn Nam1 | Junwoo Jo2 | Sun Ha Choi1 1Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, South Korea | 2Department of Statistics, Kyungpook National University, Daegu, Korea Correspondence: Su Youn Nam ([nam20131114@gmail.com](nam20131114@gmail.com)) Received: 12 August 2025 | Revised: 4 January 2026 | Accepted: 15 January 2026 Keywords: body mass index change | lung cancer | menopausal status | sex | smoking ABSTRACT While baseline body mass index (BMI) has been inversely associated with lung cancer risk, the impact of BMI change remains unclear. Furthermore, stratified analysis by menopausal status and age has not been explored. Cancer-free participants who completed National Health Examinations in 2010 and again in 2014 were included (n = 3,822,171; follow-up through 2021) . BMI was measured at both time points, and changes were categorized. We modeled competing-risk outcomes using the Fine–Gray approach to obtain adjusted hazard ratios (aHRs) and 95% confidence intervals (95% CI) . During follow-up, 43,704 lung cancer cases occurred. Persistent obesity (obesity I [25.0–29.9 kg/m2], aHR 0.93, 95% CI 0.89–0.97; persistent obesity II [≥30.0 kg/m2]: aHR 0.80, 95% CI 0.72–0.90) and transitioning from normal BMI to obesity (aHR 0.79, 95% CI 0.63–0.99) were associated with reduced lung cancer risk. Stratified analyses revealed stronger associations among men and ever smokers. Persistent obesity and BMI gain were associated with reduced risk in both men and women, whereas persistent underweight (aHR 1.24; 95% CI 1.14–1.35) and transitioning from normal BMI to underweight (aHR 1.27; 95% CI 1.17–1.39) were associated with increased risk only in men. Persistent obesity and BMI gain were associated with lower lung cancer risk in never-smokers as well as smokers, but persistent underweight (aHR 1.34, 95% CI 1.22–1.47) elevated lung cancer risk only in smokers. Age and menopausal status further modified the associations. Persistent obesity and BMI gain were protective, whereas underweight and BMI loss elevated lung cancer risk in men and smokers. Registry and the Registration no: NA 1 | Introduction Lung cancer ranks as the second common cancer in incidence and remains the foremost cause of cancer-related mortality [1] . Although the overall incidence of lung, bronchus, and tracheal cancers has declined in many regions, certain countries have experienced rising trends during the past three decades [2–5] . Epidemiologic research has reported that baseline high body mass index (BMI) was protective in lung cancer risk [6, 7] . Nevertheless, the influence of trajectory in adiposity on lung cancer development is unclear, with inconsistent findings across studies. For instance, one cohort study showed that individuals with a normal BMI in young adulthood who later became overweight or obese in midlife had a lower lung cancer risk compared with those who remained at a normal BMI [8] . In contrast, BMI change had no meaningful association with lung cancer risk [9] or BMI gain even elevated lung cancer risk [10] . A recent Chinese cohort study focusing on male never-smokers reported that both loss and gain in BMI were associated with an elevated risk of lung cancer compared to a stable BMI [11] . Previous case– control studies suggested that BMI gain showed an inverse association with lung cancer risk in current and former smokers [12] . | Abbreviations: aHR, adjusted hazard ratio; BMI, body mass index; CI, confidence interval; NGHE, National General Health Examination; NHISS, National Health Insurance Service System. | | --- | | This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provi

FAQs

How was BMI change assessed and categorized in this study?

BMI was measured at two time points (2010 and 2014), and changes were categorized based on the observed transition between BMI levels.

What modeling approach was used to estimate lung cancer risk?

The study used competing-risk outcomes modeled with the Fine–Gray approach to obtain adjusted hazard ratios (aHRs) and 95% confidence intervals.

Which BMI change patterns were associated with reduced or increased lung cancer risk?

Persistent obesity and transitions from normal BMI to obesity were associated with reduced risk. Persistent underweight and transitions from normal BMI to underweight were associated with increased risk, with sex and smoking status modifying these associations.

Sep 22, 2026

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