Physical activity is associated with a reduced risk of esophageal cancer, particularly esophageal adenocarcinoma, according to a new meta-analysis of published observational studies presented by Mayo Clinic researcher Siddharth Singh, M.D., at the American College of Gastroenterology's 78th Annual Scientific Meeting in San Diego, CA.
In a meta-analysis of four studies, Dr. Singh and his colleagues observed a 32 percent lower risk of esophageal adenocarcinoma, which can arise from Barrett's esophagus, in people who were physically active. The meta-analysis also showed the overall risk of esophageal cancer was 19 percent lower among the most physically active people, compared with the least physically active.
"Obesity has been associated with increased risk of esophageal cancer through high levels of insulin, as well as chronic inflammation. By decreasing visceral fat, lowering the level of carcinogenic adipokines, improving insulin sensitivity, and decreasing chronic inflammation, physical activity can potentially decrease risk of esophageal cancer," said Dr. Singh.
Esophageal cancer is the sixth most common cancer in men worldwide, and has a dismal five-year survival rate of approximately 15 percent, with most patients dying within the first year of diagnosis. There are two types of esophageal cancer: esophageal squamous cell, which begins in cells lining the esophagus, and adenocarcinoma, which begins in cells that make and release mucus and other fluids. Dr. Singh and colleagues note that although, "the incidence of esophageal squamous cell cancer is declining worldwide, the incidence of esophageal adenocarcinoma has been rapidly rising. This increase may be partly attributable to the obesity epidemic."
Current evidence for this link has been limited to observational studies. According to Dr. Singh it is too early to conclude that exercise directly decreases esophageal cancer risk. He proposes that physically active people may be more likely to take preventive health measures, as compared to patients who are not physically active. Thus, he says, it is possible that other healthy lifestyle behaviors aside from physical activity contribute to a lower cancer risk.
There are ongoing randomized controlled trials assessing the effect of exercise on esophageal cancer risk in patients with Barrett's esophagus.
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