Association of genetic polymorphisms of aldehyde dehydrogenase-2 with esophageal squamous cell dysplasia

Association between ALDH2 Glu487Lys polymorphism and the risk of esophageal cancer

OBJECTIVE

A meta-analysis was carried out to further evaluate the relationship between ALDH2 Glu487Lys polymorphism and esophageal cancer risk.

METHODS

A total number of 15 studies that included 3812 cases and 7376 controls were identified for our meta-analysis.

RESULTS

Our findings indicated that individuals with the combination of Glu/Lys and Lys/Lys genotype had an increased risk of getting esophageal cancer (GA + AA vs. GG: odds ratio [OR] 1.36, 95% confidence interval [CI] 0.93-2.00, P = 0.113) with a shift pattern. Although Lys/Lys genotype carriers showed areduced esophageal cancer risk (AA vs. GA + GG: OR 0.41, 95% CI 0.23-0.72, P = 0.002). Similarly, a negative association was observed under homozygote comparison (AA vs. GG: OR 0.49, 95% CI 0.29-0.85, P = 0.011). In the China subgroup analysis, the similar results were found.

CONCLUSIONS

This meta-analysis concluded that there was a strong association between ALDH2 Glu487Lys polymorphism and the risk of esophageal cancer. It further confirmed that ALDH2 Glu487Lys polymorphism was a high-risk factor for esophageal cancer.

Endoscopic screening for precancerous lesions of the esophagus in a high risk area in Northern Iran

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a major health problem in many developing countries including Iran. ESCC has a very poor prognosis, largely due to late diagnosis. As a first step in developing an early detection and treatment program, we conducted a population-based endoscopic screening for ESCC and its precursor lesion, esophageal squamous dysplasia (ESD) in asymptomatic adults from Golestan Province, northern Iran, a high-risk area for ESCC, to evaluate the feasibility of such a program and to document the prevalence and risk factor correlates of ESD.

METHODS

This cross-sectional study was conducted among participants of the Golestan Cohort Study (GCS), a population-based cohort of 50,000 adults in eastern Golestan Province. Randomly selected GCS participants were invited by telephone. Those who accepted were referred to a central endoscopy clinic. Eligible subjects were consented and then asked to fill in a brief questionnaire. Detailed information about selected risk factors was obtained from the GCS main database. Endoscopic examination with Lugol's iodine staining was performed, biopsies were taken from unstained lesions as well as the normally stained mucosa of the esophagus, and the biopsies were diagnosed by expert pathologists according to previously described criteria.

RESULTS

In total, 1906 GCS subjects were invited, of whom only 302 subjects (15.8%) were successfully enrolled. Esophagitis (29.5%) and ESD (6.0%) were the most common pathological diagnoses. Turkmen ethnicity (adjusted OR = 8.61; 95%CI: 2.48-29.83), being older than the median age (OR = 7.7; 95% CI: 1.99-29.87), and using deep frying cooking methods (OR = 4.65; 95%CI: 1.19-18.22) were the strongest predictors for ESD. There were significant relationships between esophagitis and smoking (p-value<0.001), drinking hot tea (P value = 0.02) and lack of education (P value = 0.004).

CONCLUSION

We observed a low rate for participation in endoscopic screening. Overall prevalence of ESD was 6.0%. Developing non-endoscopic primary screening methods and screening individuals with one or more risk factors may improve these rates.

Development of squamous neoplasia in esophageal iodine-unstained lesions and the alcohol and aldehyde dehydrogenase genotypes of Japanese alcoholic men

We investigated the development of esophageal neoplasia in biopsy specimens of the distinct iodine-unstained lesions (DIULs) ≥ 5 mm detected in 280 of 2,115 Japanese alcoholic men who underwent screening by esophageal iodine staining. Low-grade intraepithelial neoplasia (LGIN) was diagnosed in 155 of them, high-grade intraepithelial neoplasia (HGIN) in 57, and invasive SCC in 35. The size of the DIULs increased with the degree of neoplasia. Most LGINs were flat and were missed before iodine staining. Some DIULs became a light pink color (PC) about 2 min after staining, and 2.6, 56.1 and 96.0% of the LGIN, HGIN and invasive SCC lesions, respectively, were PC-sign-positive. Multiple DIULs of any size markedly increased the risk of LGIN [adjusted OR (95%CI) = 10.1 (7.12-14.5)], HGIN [27.9 (14.6-53.4)] and invasive SCC [21.6 (10.1-46.4)], and were strongly associated with the presence vs. absence of DIULs ≥ 5 mm [13.3 (9.21-19.1)], inactive heterozygous aldehyde dehydrogenase-2 (ALDH2*1/*2) vs. ALDH2*1/*1 [2.60 (1.79-3.78)], and less-active alcohol dehydrogenase-1B (ADH1B*1/*1) vs. ADH1B*2 allele [2.61 (1.87-3.64)]. The combination of ALDH2*1/*2 and ADH1B*1/*1 synergistically increased the risk of LGIN [4.53 (2.17-9.47)], HGIN [10.4 (4.34-24.7)] and invasive SCC [21.7 (7.96-59.3)]. Esophageal neoplasia developed at earlier ages in those with ALDH2*1/*2. Biopsy-proven HGIN was diagnosed as invasive SCC in 15 (39.5%) of 38 patients after endoscopic mucosectomy or surgery. In conclusion, large size, non-flat appearance, positive PC sign and multiplicity of DIULs and ALDH2*1/*2 and ADH1B*1/*1 were associated with development of esophageal neoplasia in Japanese alcoholics. Biopsy-proven HGIN should be totally resected for both diagnostic and therapeutic purposes.

Meta-analysis of ADH1B and ALDH2 polymorphisms and esophageal cancer risk in China

AIM: To evaluate whether alcohol dehydrogenase-1B (ADH1B) His47Arg and aldehyde dehydrogenase-2 (ALDH2) Glu487Lys polymorphism is involved in the esophageal squamous cell carcinoma (ESCC) risk in Chinese Han population.

METHODS: Seven studies of ADH1B and ALDH2 genotypes in Chinese Han population in 1450 cases and 2459 controls were included for meta-analysis. Stratified analyses were carried out to determine the gene-alcohol and gene-gene interaction with ESCC risk. Potential sources of heterogeneity between studies were explored, and publication bias was also evaluated.

RESULTS: Individuals with ADH1B arginine (Arg)/Arg genotype showed 3.95-fold increased ESCC risk in the recessive genetic model [Arg/Arg vs Arg/histidine (His) + His/His: odds ratio (OR) = 3.95, 95% confidence interval (CI): 2.76-5.67]. Significant association was found in the dominant model for ALDH2 lysine (Lys) allele [glutamate (Glu)/Lys + Lys/Lys vs Glu/Glu: OR = 2.00, 95% CI: 1.54-2.61]. Compared with the non-alcoholics, Arg/Arg (OR = 25.20, 95% CI: 10.87-53.44) and Glu/Lys + Lys/Lys (OR = 21.47, 95% CI: 6.44-71.59) were found to interact with alcohol drinking to increase the ESCC risk. ADH1B Arg+ and ALDH2 Lys+ had a higher risk for ESCC (OR = 7.09, 95% CI: 2.16-23.33).

CONCLUSION: The genetic variations of ADH1B His47Arg and ALDH2 Glu487Lys are susceptible loci for ESCC in Chinese Han population and interact substantially with alcohol consumption. The individuals carrying both risky genotypes have a higher baseline risk of ESCC.