VANCOUVER - BC Cancer Agency researchers are the first in the country to conduct a study investigating whether spiral CT scans can help increase the odds of detecting early-stage lung cancers.

A spiral CT scan provides a better quality image and is four to ten times more accurate than a conventional chest x-ray in diagnosing lung cancer. With a chest x-ray, lesions as small as a few millimetres may go unnoticed because the rib cage or spine may hide them. Lesions can also be difficult to differentiate from blood vessels on a x-ray.

The spiral CT scan is being used in conjunction with two technologies developed by BC Cancer Agency scientists -- a computerized microscope which detects abnormal cells in the sputum and the lung imaging fluorescence endoscope (LIFE) which allows researchers to see precancerous and cancerous tissue too small to detect by conventional methods.

Scientists are optimistic that the three-pronged approach will help identify precancerous and cancerous lesions when they're small enough to be treated successfully. Because early lung cancer shows no symptoms, the disease often goes undiagnosed until a late stage when the five-year survival rate is less than 15 per cent. If physicians can locate the disease earlier, however, the odds for survival could jump from 15 per cent to more than 80 per cent.

The three tests being used by researchers are complementary, according to Dr. Stephen Lam, the principal investigator of the study. The three-year study is funded by the National Cancer Institute in the U.S. The sputum test provides an indication of any cancerous or precancerous changes. If abnormal cells are detected, researchers insert the LIFE device into the lungs via a fiberoptic tube to pinpoint the source of these cells. Abnormal lesions as small as one millimetre fluoresce a reddish brown color while normal tissue appears green. While LIFE allows physicians to get into the larger bronchial passages of the lungs to detect precancerous and cancerous changes, it doesn't illuminate the small bronchial tubes or surrounding lung tissue. However, the spiral CT scan does provide an image of these areas.

"Used alone to detect lung cancers, the spiral CT scan has a high false-positive rate, especially in regions where there is a high prevalence of fungal or TB infection" says Dr. Lam. "But used in conjunction with the sputum and LIFE technology we hope to achieve both a high detection rate and a low false-positive rate."

"We hope to increase our chances of catching early stage lung cancers, particularly for women, who tend to have more peripheral cancers, located in small bronchial tubes and surrounding lung tissue, than men."

Researchers hope to recruit about 250 men and women, between the ages of 45 and 74 who have smoked a least a pack of cigarettes a day for 30 years or more to participate in the study.

Patients with precancerous changes will be invited to participate in a cancer prevention trial of Pulmicort -- a drug commonly used to treat asthma, which shows promise in halting the growth of abnormal lesions. The study also includes a smoking cessation program for participants.

For more information about recruitment, please call:
Suzan Ross, Coordinator
Lung Health Study
604-877-6190