THURSDAY, May 19, 2005 (HealthDay News) -- Obesity is associated with an increased risk of colorectal cancer, while obesity and smoking both raise the odds for throat malignancies, two new studies find.
In the first study, University of Tokyo researchers examined the effect of body mass index (BMI) -- a standard measure of obesity -- on colorectal cancer risk. They also evaluated whether weight reduction lowered the risk of colorectal cancer.
In the first part of the study, the researchers analyzed colonoscopy results for nearly 9,000 patients with either no sign of colorectal tumors, or tumors that could be removed using endoscopy. People with the highest BMIs -- the most overweight -- were most likely to have colorectal tumors.
In the second part of the study, nearly 3,000 of the patients underwent a second colonoscopy one year later. Those who had lost weight had a 10.9 percent reduced risk of colorectal tumor compared to 17.3 percent for those who did not lose weight, the Japanese team reports.
"Our study illustrates the importance of maintaining a healthy body weight in the prevention of colorectal adenoma. Patients who lower their BMI may reduce their risk of developing colorectal cancer in the future," study lead author Dr. Yutaka Yamaji said in a prepared statement.
In a different study, researchers at Queen's University Belfast, in Ireland, concluded that high BMI and smoking don't contribute to the initial development of Barrett's esophagus, a pre-cancerous condition, but may play a key role in the progression of this disorder to esophageal cancer.
Barrett's esophagus is a disorder that causes the lining of the esophagus to become damaged as a result of chronic irritation by stomach acid reflux.
"Although there is not an established link between smoking, BMI and Barrett's esophagus, patients suffering from Barrett's esophagus should avoid a high BMI and smoking to prevent the development of esophageal cancer," study senior author Dr. Liam Murray said in a prepared statement.
Both studies were presented at this week's Digestive Disease Week conference, in Chicago.
More information
The U.S. National Institutes of Health has more about colorectal cancer.
