Impact of smoking and opium cessation on gastrointestinal cancer risk: A 15-year longitudinal study in Golestan Cohort

Abstract

Smoking and opium use are risk factors for gastrointestinal cancers, yet the extent to which cessation reduces cancer risk remains unclear, particularly in non-Western populations. This study analyzed data from the Golestan Cohort Study in northeastern Iran, comprising 50,045 adults aged 40-75 years followed for a median of 15 years. Participants were classified into never-users, current smokers or recent quitters (less than 5 years), and long-term quitters (more than 5 years). For esophageal cancer, long-term quitters demonstrated substantial risk reductions (HR for smoking: 0.68; 95% CI: 0.47-0.99; HR for opium: 0.33; 95% CI: 0.12-0.90), while current users and recent quitters of both smoking and opium indicated increased risks (HR for smoking: 1.53; 95% CI: 1.14-2.07; HR for opium: 1.50; 95% CI: 1.20-1.88). For stomach cancer, long-term smoking quitters showed a protective effect, with a 35% risk reduction though no significant risk reduction was observed for long-term opium cessation. For pancreatic cancer no significant risk reduction was noted among long-term quitters. This study highlights that cessation of smoking or opium use for more than 5 years can reduce the risk of esophageal cancer, while risk reduction for other types of gastrointestinal cancers requires longer cessation duration.

Keywords: Cohort studies; Gastrointestinal neoplasms; Opium; Risk factors; Smoking cessation.

Fig. 1

The forest plot demonstrates the adjusted hazard ratios for the impact of smoking cessation on incidence of the four gastrointestinal cancers.

Fig. 2

The forest plot demonstrates the adjusted hazard ratios for the impact of opium use cessation on incidence of the four gastrointestinal cancers.