Progression of precancerous lung lesions analysed

The risk of precancerous lesions developing into lung cancer is highest among current and heavy smokers, according to a study presented by Vijay Jayaprakash, MBBS, Division of Cancer Prevention and Population Sciences, Roswell Park Cancer Institute (RPCI), at the American Association for Cancer Research (AACR) Seventh International Frontiers in Cancer Prevention Research, Washington, DC.

Normal lung tissue undergoes a series of precancerous changes before it develops into lung cancer. Metaplasia, dysplasia and carcinoma in situ (CIS) have been identified as precancerous conditions; however, not all of these lesions progress to cancer. Dr Jayaprakash, working with Mary Reid, PhD , RPCI, evaluated the risk factors and the natural progression of these precancerous lesions to lung cancer.

In this study, 124 high-risk lung cancer patients were evaluated at the Lung Cancer Screening Clinic at RPCI. Screening autofluorescence bronchoscopy (AFB) was performed on these patients at the beginning of the study and was followed up with at least one more AFB, on average 16 months later.

This study demonstrated that even low-grade precancerous lesions have the potential to progress to lung cancer. Baseline metaplasia, low-grade dysplasia and high-grade dysplasia progressed at a rate of 1.5%, 2.6% and 5.3%, respectively.

Heavier smokers and current smokers were at the greatest risk for their normal areas progressing to precancerous lesions and existing precancerous lesions progressing toward lung cancer.

Patients who reported smoking more than 50-pack-years were seven times more likely to have their normal areas progress to precancerous lesions, compared to those who had never smoked. Former and current smokers had a 2.5 times and 7 times greater risk of normal areas becoming precancerous, respectively.

Similarly, the risk of progression of existing precancerous lesions was more than two and half times greater in heavier smokers, even when compared to lighter smokers. Patients with COPD and previous asbestos exposure also showed slightly increased risk of progression of precancerous lesions.

"This study is one of a few to examine the risk factors that can influence the progression of precancerous lesions to lung cancer," said Dr Reid.

"This information will be valuable in improving the understanding of the natural history of lung cancer and to identify the high-risk population who are at a greater need of regular follow-up. This is one more important step as we continue to make progress in the prevention and early detection of lung cancer, the most common cause of cancer death."

Dr Reid shared that RPCI is currently spearheading the international Stacey Scott Lung Cancer Registry, a collaboration of centers in the United States, Canada and Europe, to help facilitate research into the characteristics and progression of lung cancer.

(Source: Roswell Park Cancer Institute: November 2008)