Lung cancer screening with low-dose chest tomography (LDCT) has been demonstrated to reduce lung cancer mortality. Preliminary reports suggested that up to 20% of lung cancers may be CT-occult but detectable by autofluorescence bronchoscopy (AFB). We evaluated the prevalence of CT occult invasive and high grade pre-invasive lesions in high risk participants undergoing screening for lung cancer.
The first 1,300 participants from 7 centers in the Pan-Canadian Early Detection of Lung Cancer Study who had 2% or greater lung cancer risk over 5 years were invited to have an AFB in addition to a LDCT. We determined the prevalence of CT and AFB abnormalities and analyzed the association between selected predictor variables and pre-invasive lesions plus invasive cancer.
A total of 776 endobronchial biopsies were performed in 333/1,300 (25.6%) participants. Dysplastic or higher grade lesions were detected in 5.3 % of the participants [n=68; mild dysplasia (n=36), moderate dysplasia (n=25), severe dysplasia (n=3), carcinoma in-situ (CIS) (n=1), carcinoma (n=4)]. Only one typical carcinoid tumor and one CIS lesion were detected by AFB alone for a rate of CT occult cancer of 0.15% [95% Confidence Interval(CI) 0.0-0.6%]. Fifty-six prevalence lung cancers were detected by LDCT (4.3%). The only independent risk factors for finding of dysplasia or CIS on AFB were smoking duration [odds ratio (95% CI)] 1.05(1.02-1.07) and FEV1% 0.99(0.98-0.99).
Addition of AFB to LDCT in a high lung cancer risk cohort detected too few CT occult cancers (0.15%) to justify its incorporation into a lung cancer screening program. (ClinicalTrials.gov number, NCT00751660.)