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Objective: To observe the effect of selenium and zinc alone or in combination on the growth and proliferation of human esophageal cancer Eca109 cell line in vitro., Methods: Different doses of sodium selenite and zinc sulfate were added into the culture medium of Eca109 cells and normal liver epithelial HL7702 cells (control), and the changes in the cell growth were assessed by means of cell growth curve, (3)H-thymidine incorporation assay and flow cytometry., Results: High-concentration selenium (0.3 micro g/ml) and zinc (3.5 microg/ml) alone both obviously inhibited Eca109 cell proliferation, and the inhibitory effect was enhanced by a combined treatment. At high concentrations, both selenium and zinc promoted HL7702 cell proliferation, but when combined, they produced inhibitory effect on the cell growth. Selenium and zinc at the physiological concentrations ( 0.1 microg/ml and 1.0 microg/ml, respectively) produced similar effects on Eca109 cells and the control cells. Selenium at 0.3 microg/ml caused Eca109 cell growth arrest in S phase, but this effect was not statistically significant; 3.5 microg/ml zinc significantly increased the number of Eca109 cells in G(1) phase. When combined, 0.3 microg/ml selenium and 3.5 microg/ml zinc caused significant G(1) arrest and promoted apoptosis of the cancer cells, an effect stronger than that of either of the agents used alone., Conclusion: High-concentration selenium and zinc show a synergetic effect in inducing growth inhibition of human esophageal cancer Eca109 cell line possibly by causing cell cycle arrest and promoting cell apoptosis, and their combined use can be toxic to normal human liver epithelial cells.

Aim: To evaluate the impact of alcohol dehydrogenase 2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2) polymorphisms on esophageal cancer risk., Methods: One hundred and ninety-one esophageal cancer patients and 198 healthy controls from Yanting County were enrolled in this study. ADH2 and ALDH2 genotypes were examined by polymerase-chain-reaction with the confronting-two-pair-primer (PCR-CTPP) method. Unconditional logistic regression was used to calculate the odds ratios (OR) and 95% confidence interval (95% CI)., Results: Both ADH2 1 allele and ALDH2 1/ 2 allele showed an increased risk of developing esophageal cancer. The adjusted OR (95% CI) for ADH2 1 allele compared with ADH2 2/ 2 was 1.65 (95% CI = 1.02-2.68) and 1.67 (95% CI = 1.02-2.72) for ALDH2 1/ 2 compared with ALDH2 1/ 1. A significant interaction between ALDH2 and drinking was detected regarding esophageal cancer risk, the OR was 1.83 (95% CI = 1.13-2.95). Furthermore, when compared with ADH2 2/ 2 and ALDH2 1/ 1 carriers, ADH2 1 and ALDH2 2 carriers showed an elevated risk of developing esophageal cancer among non-alcohol drinkers (OR = 2.46, 95% CI = 0.98-6.14), and a significantly elevated risk of developing esophageal cancer among alcohol drinkers among alcohol drinkers (OR = 9.86, 95% CI = 3.10-31.38)., Conclusion: ADH2 and ALDH2 genotypes are associated with esophageal cancer risk. ADH2 1 allele and ALDH2 2 allele carriers have a much higher risk of developing esophageal cancer, especially among alcohol drinkers.

Esophageal cancer is a crucial cancer in China. Yanting in Sichuan Province was a key area with highest esophageal cancer mortality in China, but little evidence on esophageal cancer risk factors has been reported for this area and the etiology remains unclear. To clarify risk factors, a 1:1 matched case-control study was conducted. Totals of 185 eligible esophageal cancer patients and 185 healthy residents matched for sex and age were recruited. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for possible risk/protective factors. All ORs were adjusted by family history of esophageal cancer and occupation, and then further adjusted by other possible confounding factors. Our results showed that smoking and alcohol drinking were risk factors for esophageal cancer with dose-response. The ORs (95% CI) compared with never smokers and drinkers were 4.06 (1.55-10.6) and 2.49 (1.06-5.85), respectively. The OR was further increased to 8.86 (95% CI, 3.82-20.5) for both smoking and drinking in combination. Eating food rapidly (OR=5.84, 95% CI, 2.05-16.7), drinking shallow ground water (OR=4.18, 95% CI, 1.30-13.4) and frequent intake of picked vegetables (OR=2.12, 95% CI, 1.00-4.49) appeared to increase the risk, while frequent intake of fresh fruit (OR=0.42, 95% CI, 0.19-0.89), fresh vegetables (OR= 0.62, 95% CI, 0.32-1.17) and eggs (OR=0.59, 95% CI, 0.25-1.39) decreased the risk. In conclusion, smoking and alcohol drinking are common in Yanting and main contributors to esophageal cancer. Consumption of fresh fruit and eggs are not common and high consumption of these two foods as well as fresh vegetables may decrease the risk of esophageal cancer in this area. In addition, drinking shallow ground water and eating food rapidly, as well as frequent intake of pickled vegetables, are also factors increasing the risk.