Promoter hypermethylation of resected bronchial margins: a field defect of changes?
OBJECTIVE
Histologically positive bronchial margins after resection for non-small cell lung cancer are associated with shortened patient survival due to local recurrence. We hypothesized that DNA promoter hypermethylation changes at bronchial margins could be detected in patients with no histological evidence of malignancy and that they would reflect epigenetic events in the primary tumor.


METHODS
Bronchial margins, primary tumor, bronchoalveolar fluid, and paired nonmalignant lung were obtained from 20 non-small cell lung cancer patients who underwent a lobectomy or greater resection. Disease-specific recurrence was the primary end point. The methylation status of p16, MGMT, DAPK, SOCS1, RASSF1A, COX2, and RARbeta was examined using methylation-specific polymerase chain reaction.


RESULTS
All malignancies had methylation in at least one locus. Concordance of one gene with an identical epigenetic change in the tumor or bronchial margin was observed in 85% of patients. Only one patient had methylation at the bronchial margin for a gene that was not methylated in the corresponding tumor. Median time to recurrence was 37 months (range, 5-71 months). There were two local recurrences and five metastases. There were no significant correlations between DNA methylation in tumor, margins, or bronchoalveolar fluid specimens and either regional recurrence or distant metastases.


CONCLUSIONS
Histologically negative bronchial margins of resected non-small cell lung cancer exhibit frequent hypermethylation changes in multiple genes. These hyper-methylation abnormalities are also present in the primary tumor and thus may represent a field defect of preneoplastic changes that occurs early in carcinogenesis.
Guo
Mingzhou
M
Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
House
Michael G
MG
Hooker
Craig
C
Han
Yu
Y
Heath
Elizabeth
E
Gabrielson
Edward
E
Yang
Stephen C
SC
Baylin
Stephen B
SB
Herman
James G
JG
Brock
Malcolm V
MV
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001980:Bronchi / Q000378:metabolism / Q000473:pathology*; D001992:Bronchoalveolar Lavage Fluid; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism* / Q000401:mortality / Q000601:surgery; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012008:Recurrence; D013997:Time Factors; D016896:Treatment Outcome
D019941:Cyclin-Dependent Kinase Inhibitor p16; D004247:DNA