Smoking cessation and lung cancer risk in an Asian population: findings from the Singapore Chinese Health Study.
BACKGROUND
Smoking cessation is an important strategy for reducing the harmful effects of tobacco, particularly in the prevention of lung cancer; however, prospective data on the impact of smoking cessation on lung cancer risk in Asian populations are limited.


METHODS
We studied a population-based cohort of Chinese men and women aged 45-74 years--participants of the Singapore Chinese Health Study. Information on smoking, lifestyle and dietary habits was collected at the time of recruitment in 1993-1998; and smoking status was assessed again at a second interview in 1999-2004 (mean interval 5.8 years). Participants were followed up to 31 December 2007, and incident cases of lung cancer were ascertained by linkage with population-wide registries.


RESULTS
Among 45,900 participants, there were 463 incident cases of lung cancer. Relative to current smokers, those who quit smoking subsequent to baseline assessment had a 28% decrease in the risk of lung cancer (adjusted hazard ratio (HR) 0.72; 95% CI (95% confidence interval): 0.53-0.98). The risk was less than half in ex-smokers who had quit before the first interview and maintained their status (HR 0.42; 95% CI: 0.32-0.56).


CONCLUSIONS
Reduction in lung cancer incidence with smoking cessation in Asian populations is substantial and can be observed within a few years after quitting.
Wong
K-Y
KY
Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, MD3, 16 Medical Drive, Singapore 117597, Singapore.
Seow
A
A
Koh
W-P
WP
Shankar
A
A
Lee
H-P
HP
Yu
M C
MC
D000368:Aged; D044466:Asian People; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012306:Risk; D012846:Singapore / Q000453:epidemiology; D016540:Smoking Cessation