| 摘要: | Esophageal cancer is the 6th cause of cancer death around the world 1. In Taiwan, it was ranked the 9th leading cause of cancer deaths (mortality rate: 5.0/100,000) and especially the 6th one among males (mortality rate: 9.4/100,000) in 2009 (DOH/ROC, 2009). Once diagnosed, the prognosis of esophageal cancer is very poor. The overall 5-year survival rate is < 40%, suggesting the importance to prevent the occurrence of esophageal cancer 2-4. Starting from 1996, our cooperative research team has attempted to elucidate the risks of esophageal squamous cell carcinoma (ESCC) in Taiwan because ESCC was the predominantly histological type of esophageal cancer 5,6. Our epidemiological findings showed that cigarette smoking, alcohol consumption, and betel quid (BQ) chewing are three major risks for the development of ESCC in Taiwan 5,6. Additionally, areca nut chewers were 4.4 times more likely to develop esophageal cancer than non-chewers 7. Subjects who smoke cigarette and chew betel quid had a 1.8-fold increased risk of developing esophageal cancer compared with those who only smoked. The study also showed that subjects who drink alcohol in combination with chewing betel quid had a 12.0-fold increase in developing cancer compared with subjects who drinks only 6. Since there is no concrete evidence to verify the epidemiological findings, we present an animal model to investigate the effects of betel quid chewing on the development of esophageal cancer. We assumed that areca nut might work as risk factor in esophageal tumorgenesis. Meanwhile, there was a significant inverse association between the frequency of tea consumption and esophageal SCC risk (P for trend ＜0.005). Subjects who drank unfermented tea (green tea, oolong tea, or jasmine tea) had a statistically significant 0.5-fold risk of developing esophageal cancer than those who did not drink tea 8. Green tea is the most popular unfermented tea in Taiwan. Therefore, we hypothesize green tea and the active ingredient -Epigallocatechin-3-gallate (EGCG) - may suppress tumorigenesis of the murine model induced by NMBA and arecoline. Therefore, this study used N-nitrosomethylbenzylamine (NMBA)-induced esophageal papilloma male F344 rats as the animal model to study the effect of arecoline and green tea exposure to the development of esophageal papilloma. F344 rats are treated with 500 μg/mL arecoline, NMBA, or both for 5 weeks to induce esophageal papilloma. For green tea study, we add green tea extraction or EGCG that is the principal polyphenol in green tea. |
