Burning Cancer Before it Begins
by Mark Derewicz
(filed under: internal med.)
A hot balloon. That’s what doctors in one clinical trial used to destroy precancerous cells in patients with Barrett’s esophagus, a condition that can lead to throat cancer.
When a patient has acid reflux, stomach acid continually enters the esophagus. The acid sometimes changes esophageal cells into cells similar to those found in the intestines. This is Barrett’s esophagus. In some cases the cells acquire precancerous traits and morph into adenocarcinoma, a cancer that’s difficult to treat.
Nicholas Shaheen led the first randomized clinical trial to see if radiofrequency ablation could destroy the precancerous cells. The ablation system is a set of electromagnetic coils on the surface of a balloon that is inserted into a patient’s esophagus and inflated. The coils generate enough heat to burn away the precancerous cells, but not enough to harm most of the normal cells.
After twelve months of treatment, 85 percent of patients were free of the precancerous cells and 75 percent showed no evidence of Barrett’s esophagus. In the placebo version of the treatment — inserted balloon, no heat — all patients still had Barrett’s. “I thought the results would be good,” Shaheen says, “but I was surprised they would be that good.”
This outpatient treatment can cause a burning sensation in the chest that can last three or four days. But when Shaheen uses standard laser treatment, he routinely hospitalizes patients because their lower esophagi narrow and they experience much greater pain.
Shaheen says that radiofrequency ablation can’t kill cancer cells that have spread too far or deep. He has also used liquid nitrogen to freeze abnormal cells in the esophagus. He thinks this technique might be as promising as radiofrequency ablation.
“All these treatments are variations on the same theme,” he says. “If you destroy the cancerous cells and give patients rigorous acid-suppression medication, then the normal esophageal cells come back.”
Nicholas Shaheen is the director of the Center for Esophageal Diseases and Swallowing and an associate professor of medicine and epidemiology in the School of Medicine. Patients from nineteen medical centers participated in the clinical trial. BARRX Medical Inc., which manufactures the radiofrequency ablation system, funded the study.
