Researchers enrolled 1,000 symptom-free male and female volunteers aged 60 and over, who had a history of at least 10 "pack-years"" (a pack a day for 10 years or two packs a day for five years) of cigarette smoking and no history of cancer, other than non- melanoma skin cancer. Participants were interviewed and given chest X-rays and low- dose CT scans.

According to the researchers:

• On low-dose CT, nodules were detected three times as commonly as on chest X-ray.
• Detection of malignant tumors were four times as common.
• Detection of stage I (the earliest stage of invasive lung cancer) malignant tumors were six times as common.
• Malignant tumors detected on low-dose CT were substantially smaller than those detected on chest X-ray.

"Last December the American Cancer Society co-sponsored an international workshop that examined the prevailing notion that screening for lung cancer is not effective," said Robert Smith, PhD, director of cancer screening for the American Cancer Society (ACS). "Data from the current ELCAP report was presented at this workshop and led to a strong consensus recommendation that further evaluation of the potential of low-dose CT for lung cancer screening was a very high priority."

"Former and current smokers or those with other significant risks of lung cancer who hear about the ELCAP report may want to talk with their doctors about their individual risk of lung cancer and whether they should have this test," said Dr. Smith. "At the meeting, the conference attendees concluded the available data were insufficient to recommend for or against routine screening for lung cancer."

The ELCAP study began in 1992 to assess the usefulness of annual CT screening for lung cancer. These findings may spark a debate on whether mass screenings of smokers will find early lung cancers. The ACS, along with most public health organizations, does not currently recommend screening for lung cancer.

This year 171,600 Americans are expected to be diagnosed with lung cancer, and it is estimated that 158,900 people will die of the disease. Smoking is responsible for 87 percent of lung cancers.