Betel nut and tobacco chewing; potential risk factors of cancer of oesophagus in Assam, India

Abstract

Summary Cancer of the oesophagus is the most commonly diagnosed cancer in males in Assam, in north-eastern India, and ranks second for females. The chewing of betel nut, with or without tobacco and prepared in various ways, is a common practice in the region and a case-control study has been designed to study the pattern of risk associated with different ways of preparing and chewing the nuts. 358 newly diagnosed male patients and 144 female have been interviewed together with 2 control subjects for each case chosen at random from among the attendants who accompanied patients to hospital. There were significant trends in risk ratios associated with the frequency of chewing each day, with the duration of chewing in years and with the age at which the habit was started that were apparent for both males and females and which remained significant after allowance was made for other known risk factors, notably tobacco smoking and alcohol consumption. The adjusted ratios, in comparison with non-chewers, were 13.3 M and 5.7 F for chewing more than 20 times a day, 10.6 M and 7.2 F for persons who had chewed for more than 20 years and 10.3 M and 5.3 F for those who had started before the age of 20. Among the different combinations of ingredients that were chewed the adjusted odds ratios were highest for those who had been using fermented betel nut with any form of tobacco (7.1 M and 3.6 F). The risk associated with tobacco smoking and alcohol consumption, which are high in some parts of the world, were less in Assam than those associated with the chewing of betel nut.

Independent and combined effects of alcohol intake, tobacco smoking and betel quid chewing on the risk of esophageal cancer in Taiwan

“…13 The evidence for 2-way interaction of betel quid chewing with drinking and smoking was also examined in our study. Adjusted for the third habit and possible confounding variables, the joint risks for chewing and drinking as well as chewing and smoking were fitted well by a multiplicative model, a finding that is supported by earlier studies that have shown that a substantially higher cancer risk was marked among areca nut chewers who also drank alcohol 3,23,27 or smoked tobacco. 3,23 Considering chewing with or without tobacco as a category, one multicenter case-control study in Southern India found a multiplicative interaction effect between chewing and drinking as well as chewing and smoking.…”

“…Adjusted for the third habit and possible confounding variables, the joint risks for chewing and drinking as well as chewing and smoking were fitted well by a multiplicative model, a finding that is supported by earlier studies that have shown that a substantially higher cancer risk was marked among areca nut chewers who also drank alcohol 3,23,27 or smoked tobacco. 3,23 Considering chewing with or without tobacco as a category, one multicenter case-control study in Southern India found a multiplicative interaction effect between chewing and drinking as well as chewing and smoking. 15 Although areca nut is chewed without tobacco in Taiwan, our results demonstrate that betel quid chewing modified the risk of drinking in determining the development of esophageal cancer based on an additive interaction model.…”

“…15 Another 2 studies also illustrated a synergistic effect for the combined habits of alcohol drinking with smoking and chewing. 3,27 In our study, although an especially strong risk (OR ϭ 41.2) of esophageal cancer was noticed among patients who concomitantly consumed the 3 substances, no sufficient data can be used for the exploration of 3-way interaction because there were no cancer cases in the category of non-drinking and nonsmoking chewers. Owing to areca nut chewing had a higher risk for contracting oral cancer 28 and certain oral precancers, such as oral leukoplakia and submucous fibrosis 9 than esophageal cancer.…”

“…2 The practice of chewing of betel quid varies from country to country. In India and certain parts of Southeast Asia, where casecontrol studies show an association between betel quid use and esophageal cancer, 3,5,15 tobacco is used frequently as an additional ingredient in betel quid products. In our study, a 2.9-and 2.2-fold elevated risk of contracting esophageal cancer was found to relate to areca nut chewing with a piece of Piper Betel Linn inflorescence and with betel leaf/stem and inflorescence mixed, respectively; both types of products do not use tobacco as an ingredient in Taiwan.…”

“…Studies focused on this issue were conducted in 3 regions of India by methods of case-control. 3,15,27 The highest elevated risks of esophageal cancer were all identified among persons who simultaneously practiced these 3 habits. One study further demonstrated that the combined risk for using alcohol, tobacco and betel quid was significant departure from risk-product multiplicatively.…”