Risk factors for esophageal cancer: a case-control study in South-western China

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.