Lung cancer in never-smokers

A never-smoker is conventionally someone who has smoked fewer than 100 cigarettes in their life. Lung cancer in never-smokers accounts for 15 percent of lung cancers diagnosed in the UK, which would make it the 8th commonest cancer in the country on its own (BJC Reports 2023), and 15 to 25 percent of lung cancers worldwide depending on region; counted as a separate disease it would be the 7th commonest cause of cancer death in the world (BMJ Open Respiratory Research 2026). It is a different disease from smoking-related lung cancer: overwhelmingly adenocarcinoma, commoner in women and in east Asian populations, with a low tumour mutational burden and a high rate of targetable drivers, particularly EGFR mutations and ALK fusions. The causes are only partly known. Cancer Research UK attributes 15 percent of never-smoker cases in the UK to second-hand smoke, which raises a never-smoker's risk by 31 percent; radon and outdoor air pollution account for more, and the IARC's own estimate put 114,486 male and 80,378 female adenocarcinomas worldwide in 2022 down to ambient particulate pollution. Beyond that the evidence thins: the UK Million Women Study followed 634,039 never-smoking women for 14 years, found 1,469 lung cancers and tested 34 candidate risk factors, of which only three were significant, non-white ethnicity (relative risk 2.34), asthma requiring treatment (1.32) and height of 165 cm or more (1.16). The practical consequences are that no screening programme currently offered would find these cancers early, and that the assumption a non-smoker's persistent cough is not cancer delays diagnosis; the UK's OLIVE cohort was set up in 2026 to study exactly this population.