Routine screening of people at high risk of lung cancer with low-dose CT scanning can substantially drive down the death rate, according to a controversial new study led by a team of New York researchers.

Dr. Claudia Henschke, long an advocate of the spiral CT scan, said the technique allows doctors to detect even the tiniest of tumors, even those deeply embedded in the lungs. With annual screening, she said Wednesday, lung cancers can be detected in an early treatable stage, just as mammography has helped detect early stage breast cancers.

Lung cancer is the leading global cancer killer and is almost always fatal because it is diagnosed at a late stage.

Spiral CT is a computerized scan of the body, producing detailed X-ray images. As many as 600 images from numerous angles can be taken in a single scan by the device, a computer linked to an X-ray machine.

For years, critics have cited the potential for false positives that would lead to too many unnecessary biopsies. A scan costs between $200 and $300 and is generally not covered by insurance.

But Henschke, who led investigators at 38 institutions in seven countries, demonstrated in an analysis of 31,567 people that early-stage lung cancer was detected in 85 percent of patients who were scanned annually. When tumors were found, prompt surgical removal resulted in a 10-year survival rate of 92 percent.

“This means that when you find tumors when they are small, they haven’t really had that much chance to spread throughout the body,” said Henschke, chief of chest imaging at NewYork-Presbyterian/Weill Cornell Medical Center in Manhattan. Results of her study are reported in today’s New England Journal of Medicine.

She said routine scans could reverse lung cancer’s grim statistics. Only 16 percent of cases in the United States are diagnosed at Stage I while the disease is still localized in the lungs. More than 174,000 people in the United States will be diagnosed with it this year.

Critics pointed to the “observational” nature of Henschke’s research. The study lacked a control group of people who were not screened. The National Cancer Institute currently is overseeing such a study. Others are under way.