Changing Trends Of Incidence Of Lung Cancer In Southern Thailand

Joanne CHANG, University of Michigan, United States

1 Department of Epidemiology, University of Michigan
2 Epidemiology Unit, Faculty of Medicine, Prince of Songkla University
3 Department of Environmental Health Sciences, University of Michigan

Purpose: Lung cancer is one of the leading incident cancers in Thailand (#2 in males and # 4 in females). With the greatest religious diversity in the nation, the Southern region of Thailand presents a unique heterogeneity of behavioral and dietary patterns between Thai Buddhists and Muslims.  Although the role of smoking has been well characterized, the incidence rate trends across Southern Thailand have not yet been examined by sex, religion and histology.  

​Methods: Lung cancer cases (n=3845) diagnosed from 1989-2013 were extracted from the Songkhla Cancer Registry.  Age-standardized incidence rates (ASRs) were calculated by sex, religion and histology using software R. Incidence rates were standardized using the World Standard Population (WHO 2000-2025). Annual percent change (APC) were calculated to quantify the changes in incidence rates over time using Joinpoint regression analysis.

Results: Males have higher rates of lung cancer than females (ASRs: 21.1 and 7.3 per 100,000, respectively).  Adenocarcinoma was the most common histology in both males and females (ASRs: 6.9 and 3.9 per 100,000, respectively). From 1989-2013, adenocarcinoma rates continued to increase for both males and females (APCs=4.7% and 5.7%, respectively), whereas squamous, large and small cell rates continued to decrease. In terms of religion, rates increased for Buddhist females (APC= 4.0%) and Muslim males (APC=5.4%), and both Buddhist males and females showed larger increases in incidence rates of adenocarcinoma than their Muslims counterparts.
Conclusions:  In Southern Thailand, the continuing rise in lung adenocarcinoma in both genders especially in women who are non-smokers, suggest a need to better understand factors in addition to smoking, which may be contributing to this trend. Further investigation into the prevalence of risk factors by religion in Southern Thailand is needed to explain these trends.

Funding sources: Thai Studies Grant and Rackham Research Grant, University of Michigan