Pre-existing type 2 diabetes and risk of lung cancer: a report from two prospective cohort studies of 133 024 Chinese adults in urban Shanghai.

OBJECTIVES

Observational studies of type 2 diabetes (T2D) and lung cancer risk are limited and controversial. We thus examined the association between T2D and risk of incident lung cancer using a cohort design.

SETTING

Data from two ongoing population-based cohorts (the Shanghai Men's Health Study, SMHS, 2002-2006 and the Shanghai Women's Health Study, SWHS, 1996-2000) were used. Cox proportional-hazards regression models with T2D as a time-varying exposure were modelled to estimate HRs and 95% CIs.

PARTICIPANTS

The study population included 61 491 male participants aged 40-74 years from SMHS and 74 941 female participants aged 40-70 years from SWHS.

OUTCOME MEASURE

Lung cancer cases were identified through annual record linkage to the Shanghai Cancer Registry and Shanghai Municipal Registry of Vital Statistics, and were further verified through home visits and a review of medical charts by clinical and/or pathological experts. Outcome data until 31 December 2010 for men and women were used for the present analysis.

RESULTS

After a median follow-up of 6.3 years for SMHS and 12.2 years for SWHS, incident lung cancer cases were detected in 492 men and 525 women. A null association between T2D and lung cancer risk was observed in men (HR=0.87, 95% CI 0.62 to 1.21) and women (HR=0.92, 95% CI 0.69 to 1.24) after adjustments for potential confounders. Similar results were observed among never smokers.

CONCLUSIONS

There is little evidence that pre-existing T2D may influence the incidence of lung cancer.