The effect of smoking cessation after a long-time tobacco use history on lung cancer incidence : a case-control study in western China

Abstract

Background: Prevalence of smoking among Chinese males is one of the highest around the world. Cigarette smoking is a leading cause of lung cancer contributing to high mortality and morbidity among all kinds of cancer in China. Facing the real situation that smoking in China has a long-history, regional maldistribution and a practice that is highly male skewed, we researched the effect of smoking cessation on lung cancer in long-time cigarette smokers from the western part of China. Similar studies focused on other countries or eastern and middle part of China, therefore this study focused on the western part of China which could provide encouraging message on smoking cessation to current smokers.

Objectives: Investigate the effect of smoking cessation on lung cancer incidence for people who had a long-history of cigarette smoking in western part of China and adjusted for major potential confounders.

Methods: This is a retrospective case-control study and 142 lung cancer cases were collected from medical records in Wuhai people’s hospital from January 2014 to December 2014 who had smoking over 20 years. We randomized selected controls from same hospital and same duration and matched them with cases by 5-year age group. Logistic regression was used to estimate the odd ratio (OR) and 95% confidence interval (95% CI) of former smoker to current smoker. Major risk factors were adjusted and potential confounders were included in final model. I also tested the duration-response of smoking cessation on lung cancer.

Results: OR of former smoker to current smoker for all types of lung cancer are smaller than 1, which meant that smoking cessation could lower the risk of all types of lung cancer. As for duration-response, I observed a decreased OR in first two years of smoking cessation, which indicated that risk of lung cancer decreased with quitting history in the first two years of smoking cessation.

Conclusion: The lower risk of lung cancer after smoking cessation for long-term cigarette smokers provided an encouraging message for the large number of smokers in the western part of China to quit smoking. The decrease risk of lung cancer in the first two years of smoking cessation also has clinical and public health implications for chronic smokers, clinicians and public health practitioners.