Higher doses of radiation don't up survival rates for patients stricken with stage III, non-small cell lung cancer, according to a late-breaking study shared Monday at the American Society for Radiation Oncology's annual meeting in Miami.

The researchers said the findings of the randomized, phase III trial were surprising, as most radiation oncologists believe that higher doses of radiation will cure more patients.

In the study, 423 patients were randomly assigned to a high-radiation group (receiving 74 Gy) or a normal-radiation group (receiving 60 Gy). All patients received concurrent chemotherapy, although some patients were randomly chosen to also receive weekly doses of cetuximab, a monoclonal antibody that helps slow cancer growth.

After following up with the patients for a median 9 months, the researchers closed down the high-dose research arm in June as no survival benefits were found, they said. The preliminary, one-year overall survival rate was about 75 percent, they said.

However, the researchers are still running the study to see whether the addition of the drug cetuximab improves outcomes.

"The trial crossed a futility boundary, meaning at first interim analysis it was determined that patients receiving higher dose radiation therapy could not have better survival than patients receiving 60 Gy radiation therapy," Dr. Jeffrey Bradley, radiation oncologist with Washington University School of Medicine in St. Louis, told reporters at a press conference Monday. "The standard dose should remain 60 Gy."

Bradley said the reason higher doses were not more effective is likely because most lung cancer patients die of metastasis, regardless of the dose given.

"Although I don't have the data showing patterns for failure to back that up, I suspect that's the problem," he said.

The investigators said there was no significant difference in toxicity between the two groups and that most deaths were caused by the cancer itself, although the high-dose protocol was linked with seven deaths, and the standard with three.

The standard dose for lung treatments was set in the 1980s, Bradley said, but some subsequent studies suggested higher doses of therapy would improve survival, especially as newer, more sophisticated dose-delivery technologies became available. In the current study, about 55 percent of patients received 3-D conformal radiotherapy, and about 45 percent received intensity modulated radiation therapy, both of which can help reduce the dose to healthy tissue.

Non-small cell lung cancer is the most common type of lung cancer, which kills 156,000 people in the U.S. every year, making it the leading cause of cancer deaths, according to the American Cancer Society. And about 40 percent of lung cancer patients are in stage III -- meaning the cancer is confined to the lungs and lymph nodes, Bradley said.

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