Abstract B55: Factors predicting the progression of premalignant bronchial lesions

B55 Background Lung cancer (LC) is the most common cause of cancer death in the world. Metaplasia, dysplasia and carcinoma in situ (CIS) have been identified as precursors to squamous cell carcinoma (SCC) of lung. However, the natural history of these lesions and the risk factors related to their progression has not yet been clearly described. Methods The cohort included 412 high risk patients who underwent screening autofluorescence bronchoscopy (AFB) at the Lung Cancer Screening Clinic at the Roswell Park Cancer Institute, Buffalo, New York. Follow up AFB procedures were performed on 124 patients (average 2.6 AFB/ patient), and 335 baseline lesions (134 benign, 144 metaplasia and 57 dysplasia) were followed up for an average of 16 months after their first AFB. Development of a CIS/SCC was considered to be an endpoint; otherwise patients were followed till March, 2008. Results Fourty one percent (55/134) of benign lesions progressed to higher grade lesions (46 to metaplasia and 9 to dysplasia). Among metaplasia, 46% regressed, while 38% persisted, 14.6% (21/144) progressed to dysplasia and 1.4% (2/144) progressed to CIS/SCC. Among dysplasia, 31% regressed to benign, 37% regressed to metaplasia, 30% (17/57) persisted and 1.8% (1/57) progressed to CIS/SCC. Adjusted logistic regression was used to examine the risk factors for progression of lesions. Baseline benign lesions in males had more than 3 times greater chance of progressing compared to females [Adjusted odds ratio (AOR): 3.21, 95% confidence interval (CI):1.25-8.25, p value: 0.02]; after adjusting for age, pack years of smoking and COPD history. Benign lesions identified on former smokers had almost 3 times the risk of progressing (AOR: 2.97, 95%CI: 0.26-34.2) and benign lesions on current smokers had more than 8 times the risk of progressing (AOR: 8.22, 95%CI: 0.70-96.0), compared to never smokers (p trend: 0.008). Heavier smokers were at a greater risk of their lesions progressing. In patients with >50 pack years of smoking, benign lesions had 7 times greater risk (AOR: 7.70, 95%CI: 0.57-99.8), and metaplastic lesions had 3 times greater risk of progressing (AOR: 3.50, 95%CI: 1.40-8.76), compared to never smokers. However, similar increased risk estimates were not noted for dysplasias in patients with >50 pack year of smoking (AOR: 0.82, 95%CI: 0.09-7.14). All the smoking risk estimates were adjusted for age, gender and COPD history. COPD was associated with 4 times the risk of benign lesions progressing (AOR: 4.42, 95%CI: 1.33-14.7). COPD was associated with 80% and 23% non statistically significant increase in risk of progression for metaplasia and dysplasia, respectively. Asbestos exposure was associated with more than twice the risk of metaplastic lesions progressing. Central bronchial lesions had a non statistically significant 59% greater chance of progression, compared to peripheral bronchial lesions (AOR: 1.59, 95%CI: 0.82-3.07). Left bronchial lesions had a non statistically significant 73% greater chance of progression, compared to right bronchial lesions (AOR: 1.73, 95%CI: 0.80-3.76). Conclusion Our results show that metaplastic lesions might also progress to an invasive SCC. Male gender, current smoking, heavier smoking and COPD might be associated with progression of low grade lesions to higher grade. Central and left bronchial lesions might have a slightly greater risk of progression of premalignant lesions. Citation Information: Cancer Prev Res 2008;1(7 Suppl):B55.