Acid reflux is the most common reason U.S. adults undergo a procedure where a viewing tube is put down their throat. But many people don’t need it, according to new advice from one of internal medicine’s main professional groups.

“Overuse of upper endoscopy contributes to higher health care costs without improving patient outcomes,” doctors from the American College of Physicians write in the Annals of Internal Medicine. Published studies suggest that 10% to 40% of endoscopies don’t improve patients’ health, according to the authors.

In the procedure, a doctor inserts an endoscope, a thin flexible tube equipped with a camera and a light, through the mouth of a sedated patient and into the esophagus, stomach, and first portion of the small intestine.

Despite a lack of supporting evidence, the authors write, doctors routinely use endoscopy to diagnose and manage gastroesophageal reflux disease, or GERD, which develops when stomach acid leaks into the esophagus.

Doctors use endoscopy in GERD patients mainly to check for a condition called Barrett’s esophagus, which affects about 10% of people who’ve had chronic heartburn for at least five years, says Nicholas Shaheen, MD, MPH, an author of the new advice paper. Barrett’s occurs when stomach acids damage the lining of the esophagus.

GERD and Barrett’s esophagus have been linked to an increased risk of a type of cancer called esophageal adenocarcinoma.

Although the overall risk for the cancer is still low, esophageal adenocarcinoma, which used to represent only a small minority of cancers in the esophagus, has increased 500% since the 1970s. It now accounts for more than half the cases in the U.S., says Shaheen, a gastroenterologist who directs the Center for Esophageal Diseases and Swallowing at the University of North Carolina, Chapel Hill.

While smoking and drinking are stronger risk factors for another cancer type of the esophagus, the risk of esophageal adenocarcinoma is thought to be tied to the U.S. obesity epidemic, Shaheen says. That’s in part because overweight and obese people are more likely to have GERD, he says.

“Given the rising prevalence of chronic GERD symptoms, it is perhaps not surprising that the use of upper endoscopy for GERD indications is also rising,” the authors of the advice paper write. In fact, over the past decade, there’s been an increase of greater than 40% in the use of upper endoscopy among Medicare patients.