An estimated one million people worldwide are diagnosed with lung cancer each year. A vast number of them die within five years because their condition is too advanced to treat effectively.

A new report in the -- better known as a CT scan -- before lung cancer symptoms appear can greatly reduce mortality.

The International Early Lung Cancer Action Program  - affiliated with 38 institutions in 8 countries - studied more than 31,000 men and women at high risk of lung cancer. Among the smokers or former smokers in the study, CT scans identified 484 with lung cancer. Lead author Claudia Henschke with the Weil Medical College of Cornell University says the results confirm that computerized scans can be effective tools for the early diagnosis of lung cancer. "If you were found to be in Stage I [lung cancer] and 85 percent [of participants] were found to be in that stage and you had prompt treatment, the 10-year survival rate was 92 percent."

Henschke says the advantage of a CT scan over a chest X-ray is that it can pick up tiny growths in the lung smaller than a pea or grain of rice. "You can see it much earlier when it is smaller and can't see it on the chest x-ray. Whereas if you find it early when it is still confined to that part of the lung and you cut out that part of the lung, then you are potentially cured."

Henschke says that while her research suggests the need for widespread CT screening programs, quality standards must first be put in place. "You have to train a multi-disciplinary group of test readers to analyze the results."

Henschke urges those at greatest risk - especially smokers or former smokers around age 50 - to consult their doctors about the procedure. She says 15 percent of those scanned will require a follow up test to determine the appropriate course of action.