An epidemic of heartburn has left many patients with questions about how to prevent more serious problems.

An estimated 40 million Americans are afflicted with heartburn at least once a week — putting them at risk for a range of health worries, including esophageal cancer. Nobody knows why heartburn is on the rise, but obesity and diet likely play a role. The vast majority of people with heartburn won't suffer such a serious complication, but there is little guidance on how to find out who is most at risk. As doctors debate the best advice, here is a look at some common questions.

Should I be screened? The medical community is divided on whether it's useful to screen heartburn sufferers for early signs of esophageal cancer. The most obvious sign — a change in the lining of the esophagus — has no symptoms beyond those of the underlying heartburn. This condition, known as Barrett's esophagus, typically results from years of chronic gastroesophageal reflux disease, or GERD. As many as 12 percent of the estimated 15 million GERD sufferers will develop Barrett's esophagus, and from 5 percent to 10 percent of those will go on to develop cancer.

Barrett's may be diagnosed with an endoscopy — sliding a lighted tube down the throat to get a better look at the esophagus. Patients with Barrett's should get regular screenings for cancer. The harder question is who among GERD sufferers should undergo screening endoscopy. Endoscopy costs about $1,000 and typically requires sedation.

Some researchers have suggested a one-time screening for anyone who has chronic reflux, particularly if the problem is serious enough to warrant long-term drug therapy. Others believe only those at highest risk should be screened — white men older than 40 or 50 who have suffered reflux symptoms at least twice a week for five years. Patients who develop GERD for the first time after age 65 should also consider screening.

"Nobody can be very dogmatic about this," says Stuart J. Spechler, professor of medicine at University of Texas Southwestern Medical Center in Dallas and a leading expert on Barrett's. "It's hard to know who is the best group."

• How do I know if it's serious? Anyone with chronic heartburn symptoms at least twice a week should consult a doctor. The most serious warning symptoms associated with heartburn are difficult or painful swallowing, weight loss or signs of bleeding, such as black or bloody stools. In these cases, a tumor may have already developed in the esophagus. Because esophageal cancer spreads quickly, anyone with a serious warning sign should see a doctor immediately.

• Are heartburn drugs safe to use indefinitely? Heartburn drugs aren't specifically approved for long-term use, but many doctors encourage patients to use them indefinitely.