Does chronic obstructive pulmonary disease with or without type 2 diabetes mellitus influence the risk of lung cancer? Result from a population-based cohort study.
BACKGROUND
Previous studies have suggested that chronic obstructive pulmonary disease (COPD) is an independent risk factor for lung cancer. There are some evidence that people with diabetes are at a risk of developing many forms of cancer, but inconclusive with regard to lung cancer. The aim of this study was to evaluate whether COPD with or without type 2 diabetes mellitus (T2DM) influences the risk of developing lung cancer.


METHODS
This is a retrospective cohort study consisting of 20,730 subjects newly diagnosed with COPD ("cases"). Their data was collected from the National Health Insurance system of Taiwan from 1998 to 2010. Among these patients, 5,820 patients had T2DM and 14,910 patients did not have T2DM. The retrospective matched control group consisted of 20,729 subjects without either COPD or T2DM. The control group was matched with the cases for sex, age, and index year (the year that the patient was diagnosed with COPD). The subjects were followed until the end of 2011.


RESULTS
The findings of our study showed that the risk of lung cancer was higher in the COPD group than in the non-COPD group, with adjusted hazard ratio (HR) of 5.02 [95% confidence interval (CI) = 4.23-5.94] among total case group, adjusted HR was 5.38 (95% CI = 4.52-6.40) in the cohort without T2DM and adjusted HR was 4.05 (95% CI = 3.26-5.03) in the cohort with T2DM. We observed a significantly protective effect from lung cancer (adjusted HR = 0.75, 95% CI = 0.63-0.90) of diabetic cohort than non-diabetic cohort among patients with COPD.


CONCLUSIONS
Patients with COPD had a significantly higher risk of developing lung cancer than healthy people. However, there was a protective effect of T2DM for lung cancer among patients with COPD. Further investigation may be needed to corroborate the mechanism or bring up reliable reasons.
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan; Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chu Shang Show Chwan Hospital, Nantou, Taiwan.
Te-Chun
TC
Shen
Department of Internal Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; Department of Healthcare Administration, Central Taiwan University of Science and Technology, Taichung, Taiwan.
Wei-Sheng
WS
Chung
Department of Public Health, College of Public Health, China Medical University, Taichung, Taiwan; Management Office for Health Data, China Medical University Hospital, Taichung, Taiwan.
Cheng-Li
CL
Lin
Division of Nephrology, Department of Pediatrics, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Chang-Ching
CC
Wei
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Chia-Hung
CH
Chen
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Hung-Jen
HJ
Chen
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Chih-Yen
CY
Tu
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Te-Chun
TC
Hsia
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Chuen-Ming
CM
Shih
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital and China Medical University, Taichung, Taiwan.
Wu-Huei
WH
Hsu
Department of Health Risk Management, College of Public Health, China Medical University, Taichung, Taiwan; Department of Medical Research, China Medical University Hospital, Taichung, Taiwan.
Chi-Jung
CJ
Chung
D000368:Aged; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications / Q000453:epidemiology*; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications*; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology