Aiming powerful beams of radiation precisely at tumors helped control their growth and helped people with early stage but inoperable lung cancer live longer, U.S. researchers said on Tuesday.

They said intensive radiation therapy - done in one to five treatments instead of the conventional 20 to 30 - provided more than double the rate of primary tumor control than seen in prior studies of conventional radiation therapy.

The findings suggest stereotactic body radiation therapy could “provide a significant step forward in the battle against this type of lung cancer,” Dr. Robert Timmerman of the University of Texas Southwestern Medical Center in Dallas, whose study was published in the Journal of the American Medical Association, said in a statement.

“The primary finding and perhaps most exciting aspect to this prospective study was the high rate of primary tumor control,” he said, noting that the treatment controlled tumor growth for three years in 97.6 percent of patients.

“Primary tumor control is an essential requirement for the cure of lung cancer,” Timmerman said.

Patients with early stage lung cancer generally get conventional radiation treatment, or no treatment at all, leaving the cancer to progress and kill about 60 percent of patients within two years.

For the study, the team followed 55 patients with non-small cell lung tumors whose medical conditions would not allow surgery. Radiation treatment lasted between 1.5 and two weeks.

Three years after treatment, 48.3 percent were still disease-free, and more than half - 55.8 percent - of those who got the treatment survived for three years. Overall, 20 percent of the patients died of lung cancer.

While the treatment helped control tumors in the lungs, 22 percent of patients developed tumors elsewhere in the body.

The researchers, who called these results “disappointing,” said the tumors may have been undetected during the initial screening, suggesting the need for better screening and possibly dual treatment with other cancer drugs to eliminate as much disease as possible.

Even so, Timmerman said the therapy offers “a new option that produces better outcomes and may represent an updated, and ultimately more successful, approach to the treatment of patients with early stage inoperable lung cancer.”

The study was funded by the U.S. National Institutes of Health and the Department of Defense.

Timmerman also reported receiving technology development grants from radiation device makers Varian Medical Systems of Palo Alto, California, and Elekta Instrument of Stockholm, Sweden.

Lung cancer kills around 1.2 million people a year and is the top cause of cancer death globally.

SOURCE: Journal of the American Medical Association, March 17, 2010.