Association Between Oral Leukoplakia And Risk Of Upper Gastrointestinal Cancers Deaths: Follow-Up Study In The Linxian General Population Trial

Zhao YANG, Cancer Institute/Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, China
WANG J. 2 , QU C. 3 , SHAO-MING W. 1 , LIANG H. 1 , FAN J. 1 , QIAO Y. 1

1 Department of Cancer Epidemiology, Cancer Institute/Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
2 Department of Epidemiology and Health Statistics, School of Public Health, Zhejiang University, Hangzhou, China
3 Dr. Stephen B. Gruber lab, USC Norris Comprehensive Cancer Center, Los Angeles, USA

Purpose 
Oral leukoplakia is a precancerous disorder which is common among residents in Linxian. Few studies have investigated the association between oral leukoplakia and risk of upper gastrointestinal cancers deaths. In this study, we further investigated the association between oral leukoplakia and upper gastrointestinal cancers deaths in the Linxian General Population Trial Cohort.

Methods 
A prospective cohort study was performed in the Linxian General Population Trial. Participants with oral leukoplakia were treated as an exposed group, the others were selected as a control group. All subjects were followed monthly. Hazards ratios (HRs) and 95% confidence interval (CIs) were evaluated using proportional hazards models and proportional subdistribution hazard models, respectively. 

Results 
Through May 31, 2012, there were 29 476 subjects of follow-up over a median of 27 years of observation. A total of 17 473 deaths were identified, including 2 345 esophageal squamous cell carcinoma (ESCC) deaths, 1 139 gastric cardia carcinoma (GCC) deaths, and 506 gastric non-cardia carcinoma (GNCC) deaths. Significant increased risk in ESCC mortality among exposed group versus control group was observed (9.66% vs. 7.39%). Furthermore, subjects with oral leukoplakia had a 22% higher risk of ESCC (HR: 1.22, 95%CI: 1.10 – 1.34) after adjusted covariates, especially among subjects ≤ 52 years of age at the baseline (HR: 1.32, 95%CI: 1.13 – 1.54). No significant associations were observed for GCC and GNCC deaths. 

Conclusions 
Oral leukoplakia can increase risk of ESCC death, especially in younger population. These association appear biologically plausible, and the mechanism should be investigated in further studies. 

Finding source
This work was supported by National Cancer Institute contacts [N01-SC-91030 and N01-RC-47701 to the Cancer Institute, Chinese Academy of Medical Sciences]; the international Research Program of the Division of Cancer Epidemiology and Genetics, National Cancer Institutes of Health; the Cancer Institute, Chinese Academy of Medical Sciences.