Wednesday, May 5, 2010

The Skinny on Esophageal Cancer: Obesity, Tobacco, and Screening

While the rates of many cancers have remained stable over the past decade, the rate of some esophageal cancers has been rising, and the main culprit is likely the epidemic of overweight and obesity.

Squamous cell cancers of the esophogous , a cancer type largely caused by smoking, have remained stable. But adenocarcinomas of the esophagus (including the gastric-cardia) have been rising steeply in recent years, and aside from tobacco use, most of its main risk factors are tied directly or indirectly to weight .
Directly, obesity can induce inflammation throughout the body as well as increase levels of insulin and related hormones, both of which have been linked to an increased risk of cancer. Indirectly, obesity, is also closely tied to severe acid reflux (also known as GERD) and Barrett’s esophagus, a condition where the make-up of the cell lining of the esophagus changes. Obesity increases pressure on the abdomen and stomach, which may be part of the process by which it increases risk of reflux (see figure), which in turn can increase the risk of Barrett’s esophagus.


Adenocarcinoma of the esophagus generally arises from the changes that mark Barrett’s esophagus. Yet , only a relatively few individuals with reflux or Barrett’s esophagus go on to develop cancer. This points to a role for both lifestyle and genetic factors in the transition from Barrett’s esophagus to esophageal cancer. At present, we don’t have good indicators of who will progress from Barrett’s esophagus to esophageal cancer.

Currently, screening with endoscopy (a lighted tube inserted into the esophagus) is often recommended for those with sever reflux or Barrett’s esophagus to try to catch cancers early when they’re most treatable, or even find pre-cancers that can be removed before they turn into cancer. Unfortunately, such tests have yet to be shown to be effective. Individuals with Barrett’s esophagus who have regular endoscopies don’t live longer than those who do not have regular endoscopies. In part, this is because the test isn’t as precise as we’d like. Estimates are that only 10 percent of those with suspicious test results in a high risk population (like those with reflux) actually have cancer.

Even though the science of screening for esophageal cancer is still developing, there are important steps we can take right now that can reduce the risk of the disease, and they are increasingly important as rates of the disease overall keep increasing and more than half of all cases are diagnosed at a late stage. The most promising approach is to keep acting on what we already know: Continue to combat tobacco use and take steps to stem the national (and worldwide) epidemic of overweight and obesity.

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