Prospective Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 28, 2015; 21(44): 12676-12685
Published online Nov 28, 2015. doi: 10.3748/wjg.v21.i44.12676
Gastric cancer risk in relation to tobacco use and alcohol drinking in Kerala, India - Karunagappally cohort study
Padmavathy Amma Jayalekshmi, Soroush Hassani, Athira Nandakumar, Chihaya Koriyama, Paul Sebastian, Suminori Akiba
Padmavathy Amma Jayalekshmi, Natural Background Radiation Cancer Registry, Karunagappally, Kerala 690536, India
Padmavathy Amma Jayalekshmi, Paul Sebastian, Regional Cancer Center, Trivandrum, Kerala 695011, India
Soroush Hassani, Athira Nandakumar, Chihaya Koriyama, Suminori Akiba, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan
Author contributions: Jayalekshmi PA and Sebastian P conceived and designed the study; Hassani S, Nandakumar A, Akiba S and Jayalekshmi PA conducted the statistical analysis; Jayalekshmi PA, Hassani S, Nandakumar A, Koriyama C and Akiba S prepared the manuscript.
Supported by Department of Atomic Energy, Government of India; the Health Research Foundation, Japan; and Grants-in-Aid for Scientific Research on Priority Areas of the Ministry of Education, Culture, Sports, Science and Technology of Japan, No. 12218231 and No. 1701503.
Institutional review board statement: The Regional Cancer Center, Thiruvananthapuram, India, initiated the cohort study in 1990 with the approval of ICMR, Government of India. The ethics committee of Kagoshima University Graduate School of Medical and Dental Sciences, Japan, also approved the present study.
Informed consent statement: All cohort members, or their legal guardian, provided verbal informed consent before study enrollment. Written informed consent was provided for cancer registry enrollment.
Conflict-of-interest statement: The authors confirm that this article content has no conflicts of interest.
Data sharing statement: Output files of the statistical analysis are available from the corresponding author at jayalekshminbrr@gmail.com.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Padmavathy Amma Jayalekshmi, Natural Background Radiation Cancer Registry, Karunagappally, Kerala 690536, India. jayalekshminbrr@gmail.com
Telephone: +91-476-2671833
Received: April 20, 2015
Peer-review started: April 21, 2015
First decision: June 19, 2015
Revised: July 13, 2015
Accepted: September 2, 2015
Article in press: September 2, 2015
Published online: November 28, 2015
Abstract

AIM: To assess the risk of gastric cancer (GC) in relation to tobacco use and alcohol drinking in the Karunagappally cohort in Kerala, South India.

METHODS: This study examined the association of tobacco use and alcohol drinking with GC incidence among 65553 men aged 30-84 in the Karunagappally cohort. During the period from 1990-2009, 116 GC cases in the cohort were identified as incident cancers. These cases were identified from the population-based cancer registry. Information regarding risk factors such as socioeconomic factors and tobacco and alcohol habits of cohort members were collected from the database of the baseline survey conducted during 1990-1997. The relative risks (RRs) and the corresponding 95% confidence intervals (95%CIs) for tobacco use were obtained from Poisson regression analysis of grouped survival data, considering age, follow-up period, occupation and education.

RESULTS: Bidi smoking was associated with GC risk (P = 0.042). The RR comparing current versus never smokers was 1.6 (95%CI: 1.0-2.5). GC risk was associated with the number of bidis smoked daily (P = 0.012) and with the duration of bidi smoking (P = 0.036). Those who started bidi smoking at younger ages were at an elevated GC risk; the RRs for those starting bidi smoking under the age of 18 and ages 18-22 were 2.0 (95%CI: 1.0-3.9) and 1.8 (95%CI: 1.1-2.9), respectively, when their risks were compared with lifetime non-smokers of bidis. Bidi smoking increased the risk of GC among never cigarette smokers more evidently (RR = 2.2; 95%CI: 1.3-4.0). GC risk increased with the cumulative amount of bidi smoking, which was calculated as the number of bidis smoked per day x years of smoking (bidi-year; P = 0.017). Cigarette smoking, tobacco chewing or alcohol drinking was not significantly associated with GC risk.

CONCLUSION: Among a male cohort in South India, gastric cancer risk increased with the number and duration of bidi smoking.

Keywords: Bidi smoking, Alcohol drinking, Gastric cancer, The Karunagappally cohort, Kerala, India

Core tip: In South Asia, bidi smoking is a popular form of tobacco smoking. A bidi is 0.15-0.25 g of sun-dried tobacco flakes hand-wrapped in a temburni leaf. Bidi smoking has been shown to cause various cancers, such as cancers of the lung and oral cavity, by several epidemiological studies including the Karunagappally cohort study, one of the most important cohort studies in South Asia. However, only a few studies have examined the relation between bidi smoking and gastric cancer (GC) risk. Our results indicated that GC risk increased with the number and duration of bidi smoking. To our knowledge, the present study is the first cohort study to show an association between bidi smoking and GC risk.