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

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 comm on practice in the region and a case-control study has been designed to stu dy the pattern of risk associated with different ways of preparing and chew ing the nuts. 358 newly diagnosed male patients and 144 female have been in terviewed together with 2 control subjects for each case chosen at random f rom among the attendants who accompanied patients to hospital. There were s ignificant trends in risk ratios associated with the frequency of chewing e ach day, with the duration of chewing in years and with the age at which th e 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 adjust ed odds ratios were highest for those who had been using fermented betel nu t with any form of tobacco (7.1 M and 3.6 F). The risk associated with toba cco smoking and alcohol consumption, which are high in some parts of the wo rld, were less in Assam than those associated with the chewing of betel nut . (C) 2001 Cancer Research Campaign.