By Brenda Tilke

A CT lung cancer screening program for high-risk patients over age 60 detects cancers as small as 4 mm, about one-sixth the size of cancers seen with radiography, according to findings presented during a special focus session on Tuesday.

Moreover, most of the malignancies were found at their earliest point-stage IA-with five-year survival rates of more than 80%. With conventional diagnostic tools, the overall lung cancer survival rate is only 12%, said Dr. Claudia I. Henschke, division chief of chest imaging at Weill Medical College of Cornell University.

"Lung cancer is considered a silent killer because there are no early warning signs," Henschke said. "By the time it's detected, lung cancer is typically the size of an orange. By screening with CT, cancers can be found when they're smaller than a grain of rice."

Henschke's data are based on second-year results of the Early Lung Cancer Action Program (ELCAP) developed at Weill Medical College. The data include results of CT screening of 808 smokers and former smokers who smoked a pack of cigarettes or more every day for at least 10 years, or two packs a day for five years.

The repeat screenings found 78 nodules, of which nine were malignant. The others were associated with pneumonia, viral inflammation or benign calcifications.

In addition to finding small, resectable tumors, the CT screening program has helped spur participating patients to give up or cut back on smoking. Nearly one-quarter (23%) of participants told researchers they had stopped smoking altogether and another 23% said they had substantially reduced the number of cigarettes they smoked.