Researchers said on Monday they stopped a trial of the targeted lung cancer drug Iressa after finding it did not help patients whose disease had spread.

It was another blow for the drug, known generically as gefitinib and made by AstraZeneca Plc.

Iressa specifically works against non-small-cell lung cancer, the most common and deadly form of the disease. It saves between 15 percent and 30 percent of all patients.

When first released, Iressa excited doctors because it was the first drug to work really well against lung cancer. Most patients suffering from lung cancer are killed by the disease, which is the biggest cancer killer in most of the world.

In the latest trial, researchers were seeing if Iressa would help patients with inoperable stage III lung cancer that had spread to nearby lymph nodes and tissue.

“Review of interim data indicated that gefitinib would not improve survival,” the National Cancer Institute, which led the study, said in a statement.

The 672 patients completed a chemotherapy regimen of cisplatin and etoposide with radiation, followed by docetaxel.

“Based on the analysis, the use of gefitinib following chemotherapy and radiation should not be prescribed for this group of patients,” said Dr. Scott Saxman, who oversees lung cancer clinical trials for NCI.

An estimated 172,570 people will be diagnosed with lung cancer in the United States in 2005. Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer-related death.

“An estimated 163,510 deaths from lung cancer will occur in 2005 in the United States, accounting for about 29 percent of all cancer-related deaths in the nation,” the NCI said.

The researchers will present detailed results at the American Society of Clinical Oncology Annual Meeting in Orlando, Florida, next month.

At least one team of researchers is trying to find out if lung cancer patients can be screened genetically to identify those likely to be helped by Iressa.