Abstract 6460: Smoking initiation at young age increases risk of gastric cancer among Korean men
Authors: Lee Hwi-Won , Shin Woo-Kyoung , Huang Dan , la Torre Katherine De , Yang Jae Jeong , Song Minkyo , Shin Aesun , Lee Kyoung-Mu , Lee Hyuk-Joon , Lee Jong-koo , Kang Daehee 
Published: June 2023

Abstract
Objective: Early initiation of smoking is associated with adverse health outcomes. This study aimed to investigate the association of various smoking-related factors with the risk of gastric cancer in a population with a high incidence rate of gastric cancer.
Method: From 2004 to 2013, Korean adults 40-69 years of age were enrolled in the large-scale prospective cohort, the Health Examinees-Gem study. Incident gastric cancer cases were identified until December 31, 2017, through linkage to the Korea Central Cancer Registry. Participants’ information regarding socio-demographics, smoking-related factors, and other lifestyle factors was obtained via self-reported questionnaires. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for gastric cancer risk associated with smoking-related factors such as smoking duration, amount, pack-years, and age of smoking initiation.
Results: Among 44,207 men included in the final analysis, 565 gastric cancer cases were identified during a mean (±SD) follow-up period of 8.6 (±2.0) years. Compared to non-smokers, current smokers who smoked for more than 35 years (HR 1.44, 95% CI 1.06-1.96) or with ≥30 pack-years of smoking (HR 1.40, 95% CI 1.05-1.87) were positively associated with gastric cancer. These associations were shown to be significant with increasing smoking years (p trend 0.019) and pack-years (0.016) as well. Compared to non-smokers, current smokers who initiated smoking at a younger age, before or at 20 years, were at a higher risk of gastric cancer (HR 1.46, 95% CI 1.10-1.93). No significant associations were observed among former smokers. When stratified by smoking duration, increased risk of gastric cancer was observed among those who smoked for more than 25 years in the younger smoking initiation age group (≤20 years; HR 1.50, 95% CI 1.15-1.94). In terms of smoking intensity, those who smoked less than 20 cigarettes or 1 pack a day showed an increased risk of gastric cancer in the younger smoking initiation age group that began smoking before or at 20 years of age (HR 1.78, 95% CI 1.30-2.44).
Conclusion: Our findings suggest that earlier initiation of smoking is associated with a greater risk of gastric cancer. Among those who began smoking early, longer duration is an important factor, but increased gastric cancer risk was also observed among those who smoked moderate amount on a daily basis. Thus, measures to manage and control onset age of cigarette smoking among teenagers may be considered when taking actions against the health burden of gastric cancer.
Citation Format: Hwi-Won Lee, Woo-Kyoung Shin, Dan Huang, Katherine De la Torre, Jae Jeong Yang, Minkyo Song, Aesun Shin, Kyoung-Mu Lee, Hyuk-Joon Lee, Jong-koo Lee, Daehee Kang. Smoking initiation at young age increases risk of gastric cancer among Korean men. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6460.