Background

Lung cancer was the second most diagnosed cancer (2.2M new cases) and leading cause of global cancer deaths (1.8M) in 2020. Lung cancer in the early stages is typically asymptomatic, with patients presenting with symptoms most commonly diagnosed at advanced stages. Early-stage lung cancer has a better prognosis with Stage 1 patients having a 67.7% five-year survival vs 17.1% and 3.2% for Stages III and IV respectively. Early detection and intervention have potential to reduce burden of disease. We aimed to evaluate detection of lung cancer, stage at diagnosis, available disease-specific mortality and survival rates in high-risk, never-smoking populations in order to contribute to an understanding of whether or not high-risk never-smokers warrant inclusion in targeted screening programs.

Method

Following PRISMA reporting guidelines, a systematic review was undertaken via Pubmed, Medline, Web of Science, NIH U.S National Library of Medicine Clinical Trials, EU Clinical Trials Register, Science Direct and Google Scholar. Screening of results, data extraction and risk of bias were independently undertaken by different members of the research team and the synthesised results narratively described. Only English language results were included.

Results

Twelve non-randomised studies were included, with a range of non-smoking risk factors (East Asian origin, family history of lung cancer, second-hand smoke, exposure, chronic obstructive pulmonary disease and kitchen fume exposure). Prevalence of lung cancer was 0.62% for all never-smokers, 1.15% for East Asian females and 2.6% for individuals with emphysema. Lung cancer was detected at Stage I in 87.1% of cases identified in the literature. Five and ten-year survival was 96% or higher among screened individuals with lung cancer in the two studies which reported it.

Conclusion

Those at higher risk of lung cancer and who received screening were mainly detected in Stage I. This appears to equate to an improved 5-year survival rate. Though the majority of the studies were non-randomised and of moderate to low quality, and therefore provide insufficient evidence to change clinical practice, the review, however, does highlight the need for further, higher quality research in this area. 

Impact statement

This research has the impact to inform future lung cancer screening efforts among higher risk, non smokers.