Tea drinking and the risk of biliary tract cancers and biliary stones: A population‐based case–control study in Shanghai, China

Abstract

Biliary tract cancers, encompassing tumors of the gallbladder, extrahepatic bile ducts and ampulla of Vater, are rare but highly fatal malignancies. Apart from gallstones, etiologic factors for biliary tract cancer are not clearly defined. Several epidemiologic studies have suggested that consumption of tea, especially green tea, is protective against a variety of cancers, including gastrointestinal malignancies. As part of a large population-based casecontrol study of biliary tract disease in Shanghai, China, we evaluated the effects of tea consumption on the risk of biliary tract cancers and biliary stones. The study included 627 incident cases with biliary tract cancer, 1,037 cases with biliary stones and 959 randomly selected controls. Study subjects were interviewed to ascertain data on demographic, medical and dietary factors, including tea consumption. Forty-one percent of the controls were ever tea drinkers, defined as those who consumed at least 1 cup of tea per day for at least 6 months. After adjustment for age, education and body mass index, among women, ever tea drinkers had significantly reduced risks of biliary stones (OR 5 0.73, 95% CI 5 0.54-0.98) and gallbladder cancer (OR 5 0.56, 95% CI 5 0.38-0.83). The inverse relationship between tea consumption and gallbladder cancer risk was independent of gallstone disease. Among men, tea drinkers were more likely to be cigarette smokers, and the risk estimates were generally below 1.0, but were not statistically significant. Further studies are needed to confirm these results in other populations and clarify the hormonal and other mechanisms that may be involved. ' 2006 Wiley-Liss, Inc.Key words: biliary tract cancers; gallstones; tea consumption; polyphenol; epidemiology Biliary tract cancers, consisting of tumors of the gallbladder, extrahepatic bile ducts and ampulla of Vater, are rapidly fatal. 1,2 Although these cancers are uncommon in most parts of the world, incidence rates are elevated among native Americans and Hispanics living in the United States and among populations in Central and South America, Eastern Europe and Japan.1,2 Because of the rarity and high fatality of biliary tract cancers, little is known about their etiology apart from a strong link with gallstones. 2A number of epidemiologic studies have suggested that consumption of tea, especially green tea, is protective against certain cancers, including tumors of the lung, stomach, pancreas and esophagus.3-6 The antitumor effects of green tea have been attributed to polyphenols, which in laboratory studies have demonstrated inhibitory effects on tumor growth.7-10 Results of epidemiologic studies examining the association between tea consumption and biliary tract cancer have been mixed, perhaps due to the small number of cases, different types of tea consumed and lack of data on potential confounding factors, such as gallstone disease, diet and cigarette smoking. [11][12][13][14] In this report, we evaluate the effect of tea consumption on the risk of biliary tract cancers and biliary...

Family history of gallstones and the risk of biliary tract cancer and gallstones: A population‐based study in Shanghai, China

“…[13][14][15][16][17][18][19][20] Briefly, cancer cases newly diagnosed with primary biliary tract cancer (ICD-9 156) between 1997 and 2000 were identified through a rapid-reporting system established by the Shanghai Cancer Institute with 42 collaborating hospitals in urban Shanghai. This system captured more than 95% of all biliary tract cancers diagnosed in Shanghai.…”

Tea consumption and risk of gallbladder cancer: A meta-analysis of epidemiological studies

“…Exclusion of women from studies on tea and gallbladder cancer risk yielded similar results (OR=0.62, 95% CI: 0.35-1.10, P=0.10), with significant heterogeneity (I 2 =81%; P=0.0003) (16). Following exclusion of 3 studies with a small sample size, the pooled results were not affected (OR=1.09, 95% CI: 0.80-1.48, P=0.60) and no significant heterogeneity was observed among the remaining studies (I 2 =0%; P=0.76) (17,19,20).…”

“…Our meta-analysis included a total of 6 studies [4 case-control (17,(19)(20)(21) and 2 cohort studies (16,18)] published between 1987 and 2012. The literature search and selection process is summarized in Fig.…”

“…The remaining 371 articles were reviewed; of these, the majority were excluded following title and abstract review (reviews, letters, or studies not relevant to our meta-analysis were excluded), leaving 10 studies for full-text review. A further 2 studies were excluded [one study with unavailable data for analysis (24) and one study published using English and Chinese (25)]. Following fundamental research exclusion of another 2 studies (14,15), a total of 6 studies were included in our present meta-analysis.…”

“…Certain studies reported that tea consumption significantly decreased the risk of gallbladder cancer, whereas others reported a non-significant negative correlation (16)(17)(18)(19)(20)(21). However, to the best of our knowledge, there is currently no published meta-analysis investigating the…”