Promoter methylation of genes in bronchial lavages: a marker for early diagnosis of primary and relapsing non-small cell lung cancer?
A prospective screening program, including CT, autofluorescent bronchoscopy, biopsies and bronchial lavage (BL) collection, was initiated with the specific goal of identifying biomarkers for the early detection of non-small cell lung cancer. We report and discuss the results of p16, DAPK, MGMT, FHIT and APC methylation analysis in the 126 first patients: 77 at high risk of cancer and 49 followed up after primary cancer resection. Positive results were found in 49% of BLs, 53% in current smokers and 43% in former smokers. In presence of peripheral tumours, only 38% of BLs were abnormal versus 73% in presence of central tumours, 50% in presence of preneoplasic lesions and 47% in absence of lesions. FHIT methylation was an early event, observed in one-third of the BLs from patients with or without lesions as well as in tumours. APC methylation was a late event observed in 33% of tumours but rarely in BLs. p16 was methylated in 17% of BLs but in 48% of tumours; DAPK in 15% of BL and 22% of tumours. MGMT methylation was rare. Among patients followed up after cancer surgery, 14 were in remission with normalised BL, whereas three had positive BLs and relapsed with a central tumour. Thus, gene methylation in BL might help to detect central tumours but a CT is crucial for peripheral cancer detection.