In a trial sponsored by the National Cancer Institute, 644 patients who were diagnosed with so-called GIST were treated with surgery and then assigned to receive either Gleevec -- sold by Novartis -- or placebo in hopes of preventing recurrence of the disease.

Two years later, 90 percent of the patients receiving Gleevec were alive and with no signs of cancer, compared to 71 percent of patients on placebo.

At that point, the trial was stopped and all patients were offered Gleevec, doctors said at the 43rd annual meeting of the American Society of Clinical Oncology in Chicago.

"This highly significant result could prompt re-evaluation of clinical practice recommendations for management of intermediate- and high-risk primary resectable GISTs," said principal investigator Ronald DeMatteo, vice chair of the department of surgery at Memorial Sloan-Kettering Cancer Center in New York.

"Conventional chemotherapy agents have been notoriously ineffective in GIST. This study demonstrated for the first time that targeted molecular therapy reduces the rate of recurrence after complete removal of a primary GIST," he said.

The difference in outcomes was significant after one year, DeMatteo noted. After 12 months, 97 percent of Gleevec patients were alive and disease-free, compared to 83 percent of patients on placebo.

He said that translated to an 82 percent reduction in the risk of disease recurrence.

More than 1,500 cases of the disease are diagnosed each year in the United States.