Risk factors for the development of lung cancer among never smokers: A systematic review

Zixuan Zhang; Xuewei Zhang; Yinyan Gao; Yancong Chen; Lang Qin; Irene Xy Wu

doi:10.1016/j.canep.2022.102274

Risk factors for the development of lung cancer among never smokers: A systematic review

Cancer Epidemiol. 2022 Dec:81:102274. doi: 10.1016/j.canep.2022.102274. Epub 2022 Oct 7.

Authors

Zixuan Zhang¹, Xuewei Zhang², Yinyan Gao¹, Yancong Chen¹, Lang Qin¹, Irene Xy Wu³

Affiliations

¹ Xiangya School of Public Health, Central South University, Changsha, China.
² Health Management Center, Xiangya Hospital, Central South University, Changsha, China; Centre for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China; National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China. Electronic address: zhangxuewei@sklmg.edu.cn.
³ Xiangya School of Public Health, Central South University, Changsha, China; Hunan Provincial Key Laboratory of Clinical Epidemiology, China. Electronic address: irenexywu@csu.edu.cn.

PMID: 36209662
DOI: 10.1016/j.canep.2022.102274

Abstract

This review aimed to summarize the up-to-date evidence on non-genetic factors for the development of never smoking lung cancer (NSLC) and to explore reasons behind the conflicting results. Relevant literature was searched in three electronic databases (PubMed, Embase and Web of Science) from 1 January 2000-31 July 2022. Cohort studies that investigated non-genetic risk factors for primary lung cancer in never smokers were included. The effect of non-genetic factors about NSLC were summarized with pooled relative risk (RR) and 95 % confidence intervals (CIs) through meta-analysis or narrative description when unexplained statistical heterogeneity was observed. The Newcastle-Ottawa Scale was used to appraise the methodological quality of included studies. Sixty cohort studies were included, covering population from Asia, Europe and America. Most included studies (42, 70.0 %) were of high methodological quality. Over 50 years old (RR = 5.26), environmental tobacco smoke (Pooled RR = 1.30), Chronic obstructive pulmonary disease (COPD) (RR = 2.67), family history of lung cancer (Pooled RR = 1.83) and higher level of neutrophil-lymphocyte ratio (RR = 1.73) increased the risk of NSLC. Dairy foods consumption (RR = 0.79), isoflavone intake (Pooled RR = 0.65), and riboflavin intake (RR = 0.62) decreased the risk among female population. Inconsistency or unclear definition for never smokers and risk factors could be observed in included studies. Most life behavior factors associated with NSLC can be modified through lifestyle changes. Future cohort studies are suggested to adopt a clearer definition on never smokers and exposure, conducting subgroup analysis when evidence indicating there is heterogeneity between genders, and explore dose-response relationship between the identified factors and NSLC.

Keywords: Lung cancer; Meta-analysis; Never smokers; Risk factors; Systematic review.

Publication types

Review