Siddharth Singh, MBBS
A meta-analysis of nearly 2000 patients has shown that physical activity may substantially reduce the risk of developing esophageal cancer, especially esophageal adenocarcinoma, according to results presented at the American College of Gastroenterology's Annual Scientific Meeting.
“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," Siddharth Singh, MBBS, a gastroenterologist at the Mayo Clinic, said in a statement.
To explore this hypothesis, researchers at the Mayo Clinic collected data from 8 observational studies and examined the association between recreational and/or occupational physical activity and esophageal cancer risk. The meta-analysis showed that the risk of developing esophageal cancer was 19% lower in the most physically active participants compared to the least physically active participants (5 studies, 1217 cases of esophageal cancer; odds ratio [OR]= 0.81; 95% CI, 0.67-0.99)
It was also observed that physical activity reduced the risk of esophageal adenocarcinoma by 32% (4 studies, 506 cases of esophageal adenocarcinoma; OR = 0.68; 95% CI, 0.55-0.85) but physical activity did not appear to reduce the risk of esophageal squamous cell carcinoma (2 studies, 674 cases of esophageal squamous cell cancer; OR = 0.46; 95% CI, 0.08-2.73).
Moreover, researchers noted, the type of physical activity impacted the level of risk. The analysis found that recreational physical activity was associated with a 17% reduction in risk of esophageal adenocarcinoma compared to occupational physical activity (3 studies; OR = 0.83; 95% CI, 0.69-1.00).
The National Cancer Institute (NCI) estimates that 69% of adults in the United States are overweight or obese (defined as a body mass index >25). Moreover, esophageal adenocarcinoma is one the most common cancers associated with obesity, according to the NCI.
Obese or overweight individuals are likely to experience gastroesophageal reflux disease or Barrett esophagus, which are associated with an increased risk of esophageal adenocarcinoma. The chronic low-level inflammation associated with obesity may act to worsen these conditions.
“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,” according to the study’s senior author Prasad Iyer, MD, from the Mayo Clinic.
Data on a higher incidence of esophageal cancer in people who are overweight and obese is well document. However, evidence that physical activity reduces the risk of esophageal cancer has been limited to observational studies. As a result, it is still too early to determine if physical activity directly decreases the risk of esophageal cancer, Singh suggested.
If existing trends continued, some projections estimate that by 2030 obesity will contribute to 500,000 additional cases of cancer in the United States. Esophageal cancer, which is the sixth most common cancer in men worldwide, has a 5-year survival rate of approximately 15%, with most patients dying within the first year of diagnosis.
"Esophageal cancer is a deadly disease. On average only 1 in 6 people survive to 5 years, and that's with chemotherapy and radiation as well as surgery. It's an intensive treatment. So we would be best served if we can prevent this cancer, especially in patients with high risk for developing these cancers," Singh said in a video interview.