The future burden of lung cancer attributable to current modifiable behaviours: a pooled study of seven Australian cohorts

Evaluating risk factors for lung cancer among never-smoking individuals using two Australian studies

PURPOSE

Lung cancer (LC) in never-smoking individuals would rank as Australia's eighth most deadly cancer, yet risk factors remain uncertain. We investigated demographic, lifestyle and health-related exposures for LC among never-smoking Australians.

METHODS

Using the prospective 45 and Up Study with 267,153 New South Wales (NSW) residents aged ≥ 45 years at recruitment (2006-2009), we quantified the relationship of 20 potential exposures with LC among cancer-free participants at baseline who self-reported never smoking. Adjusted hazard ratios (HR) and 95% confidence intervals (CI) for incident LC were estimated using Cox regression. The NSW Cancer, Lifestyle and Evaluation of Risk (CLEAR) Study, a case-control study including 10,781 NSW residents aged ≥ 18 years (2006-2014), was used to examine 16 potential LC exposures among cancer-free never-smoking participants. Adjusted odds ratios (OR) and 95% CI of LC were estimated using logistic regression.

RESULTS

There were 226 LC cases among 132,354 cancer-free 45 and Up Study participants who reported never smoking, with a median follow-up of 5.41 years. The CLEAR Study had 58 LC cases and 1316 cancer-free controls who had never smoked. Analyses of both datasets showed that Asian-born participants had a higher risk of LC than those born elsewhere: cohort, adjusted HR = 2.83 (95% CI 1.64-4.89) and case-control, adjusted OR = 3.78 (1.19-12.05). No significant association with LC was found for other exposures.

CONCLUSION

Our findings support the growing evidence that never-smoking, Asian-born individuals are at higher risk of developing LC than those born elsewhere. Ethnicity could be considered when assessing potential LC risk among never-smoking individuals.

Magnitude, temporal trends and inequality in global burden of tracheal, bronchus and lung cancer: findings from the Global Burden of Disease Study 2017

Introduction

We aimed to assess the magnitude, temporal trends and socioeconomic disparity in the global burden of tracheal, bronchus and lung (TBL) from 1990 to 2017, using data extracted from the Global Burden of Diseases study (GBD 2017).

Methods

We extracted data from the GBD 2017 study. A series of comparative and descriptive analyses of the disease burden between females and males and countries with different socioeconomic development statuses (Social Demographic Index, SDI). We also analysed the temporal trends of age-standardised disability-adjusted life year rates (ASDR) of TBL cancer at the global and super-regional level by means of joinpoint regression. Finally, we also calculated Concentration Index to explore trends of between-country inequality in cancer burden from 1990 to 2017.

Results

During the past 27 years, the global incidence of TBL cancer cases and death cases has increased by 100% and 82.3% respectively, but the increase number was mainly influenced by population growth and ageing. After adjustment, from 1990 to 2017, the ASDR of TBL has increased by 3% and the age-standardised death rate has decreased by 7%. The global TBL cancer burden fell by 15.3%. The joinpoint analysis revealed that the overall trend of age-standardised TBL cancer burden for both females and males significantly changed twice between 1990 and 2017, and it varied across countries with different SDI values and was also different between females and males. Age-standardised TBL cancer burden was more concentrated in higher socioeconomic development countries, but the development of healthy inequality showed a downward trend in males while showing an upward trend in females.

Conclusion

The magnitude and temporal trends of TBL cancer burden varied across countries and sex. This study highlighted the importance of crafting health policy to adapt to local conditions to manage the global burden of TBL cancers.

Association Between Physical Activity and Lower Risk of Lung Cancer: A Meta-Analysis of Cohort Studies

Background: Epidemiological evidences regarding the association between physical activity and the risk of lung cancer are still controversial.

Objectives: We aimed to investigate the relationship between physical activity and risk of lung cancer in men and women, as well as other high-risk populations such as cigarette smokers.

Methods: We conducted a meta-analysis of cohort studies to evaluate the association between physical activity and risk of lung cancer. Relevant studies were identified by searching PubMed and Web of Knowledge through August 2018. Study-specific relative risk (RR) with 95% confidence interval (CI) were pooled using random effect model when significant heterogeneity was detected.

Results:Twenty cohort studies with a total of 2,965,811 participants and 31,807 lung cancer cases were included. There was an inverse association between the physical activity and risk of lung cancer. Compared with the low level of physical activity, the pooled RR was 0.83 (95%CI: 0.77, 0.90), with significant heterogeneity (I² = 62.6%, P_{heterogeneity} < 0.001). The corresponding pooled RRs were 0.90 (95%CI: 0.82, 0.99) for women and 0.81 (95%CI: 0.73, 0.90) for men. Smokers with a high level of physical activity were associated with a 10% lower risk for lung cancer (RR = 0.90, 95% CI: 0.84, 0.97), while the association was not significant among non-smokers (RR = 0.95, 95% CI: 0.88, 1.03). Subgroups analysis stratified by whether the studies adjusted for smoking intensity and durations yielded the same magnitude of RR. However, the RR for subgroups without adjustment for dietary factors was 0.74 (95%CI: 0.71, 0.77), which was significantly lower than that with dietary factors adjusted (RR = 0.89, 95%CI: 0.84, 0.95).

Conclusions:Increased physical activity might be associated with lower risk of lung cancer. Such inverse association was identified among smokers rather than non-smokers. Large interventional studies are expected to further verify these findings.