NEW YORK, March 06 (Reuters) -- The small intestine makes up 75%, or a full 20 feet of the digestive tract, yet rarely do cancers develop there, more often showing up in the large intestine, or colon. Overall, small bowel cancers comprise less than 0.5% of all cancers diagnosed in the U.S.
However, a new study has shown that heavy alcohol consumption, as well as high sugar intake, are associated with an increased risk of small intestine cancer, called adenocarcinoma. And for men, smoking cigarettes and a heavy consumption of heterocyclic amines -- substances found in fried bacon, ham, and barbecued or smoked meat and fish -- increase the risk as well, according to a report in the International Journal of Cancer.
"In men and women combined, a significant three-fold increased risk in heavy drinkers -- more than 80 grams (2.8 ounces) of ethanol per day -- relative to more moderate drinkers and nondrinkers was observed," reported Dr. Anna Wu, of the department of preventive medicine at the University of Southern California /Norris Comprehensive Cancer Center in Los Angeles. Those who consumed the most sugar (more than 25 grams of sugar a day), mainly from that added to coffee or tea or from nondiet soft drinks, had four times the risk of small bowel cancer as those who ate the least (less than 5 grams).
In men, but not women, smoking cigarettes or eating heterocyclic amine-rich foods -- a suspected carcinogen -- more than six times a week more than tripled the risk of adenocarcinoma. The study included 36 cancer patients and nearly 1,000 of their healthy, same-age counterparts.
"At this time we can only speculate about the mechanisms by which tobacco smoke and alcohol increase the risk of small intestinal cancer," Wu wrote. "Carcinogenic chemicals have been identified in tobacco smoke," she noted. And smoking may affect how quickly the food passes through the intestine, which could have an impact on acid secretion or the bacteria that aids digestion. Alcohol also may alter digestion or irritate the digestive tract -- making it more susceptible to carcinogens.
The link between cancer and sugar intake is preliminary, but cannot be ruled out as a chance finding, the authors noted.
"Our questions on dietary factors were crude, and sugar intake from only three beverages (tea, coffee and carbonated soft drinks) were covered," they noted. The number of people included in the study was small and larger studies are needed to confirm the findings.
"In particular, better assessment of sugar intake from beverages and foods will be needed to characterize this suggested association," they concluded.
SOURCE: International Journal of Cancer (1997;70:512-517)
