Methylation assay for the diagnosis of lung cancer on bronchial aspirates: a cohort study.
OBJECTIVE
Recent studies have detected aberrant promoter methylation of adenomatous polyposis coli promoter 1 A (APC), cyclin-dependent kinase inhibitor-2A (p16(INK4a)), retinoic acid receptor beta2, and RAS association domain family protein 1 (RASSF1A) in bronchial aspirates and suggested their use as biomarkers for lung cancer diagnostics. The purpose of this study was to validate these candidate marker genes in a retrospective cohort study.


METHODS
Bronchial aspirates collected from a cohort comprising 247 patients with suspected lung cancer were investigated retrospectively regarding aberrant promoter methylation using a quantitative methylation-specific real-time PCR (QMSP).


RESULTS
Eighty-nine patients were diagnosed with primary lung cancer, 102 had benign lung disease, and 56 showed miscellaneous other conditions. A panel consisting of APC, p16(INK4a), and RASSF1A emerged as useful combination. This panel detected aberrant methylation in bronchial aspirates of 22 of 35 (63%) and 21 of 44 (44%) centrally and peripherally located primary lung cancers, respectively. Bronchial aspirates also showed aberrant methylation in 5 of 7 (71%) patients with a recurrent lung cancer and in 8 of 30 (27%) cases without tumor recurrence. In contrast, only 1 of 102 patients with benign lung disease displayed a (false) positive test result. Rarely, aberrant methylation was found in patients with other malignancies (3 of 16). The QMSP assay correctly confirmed lung cancer in 8 of 12 (67%) cases with an ambiguous cytology. Moreover, it disclosed 9 of 26 (35%) of peripheral tumors lacking simultaneous cytologic or histologic diagnosis of malignancy.


CONCLUSIONS
Our findings suggest that the QMSP assay could be applied as a reflex test in cases of suspected lung cancer that defy a definite diagnosis by conventional methods. Thus, the assay could be a useful diagnostic adjunct especially regarding peripheral tumors.
Schmiemann
Viola
V
Institut fuer Cytopathologie, Heinrich-Heine-Universitaet, Duesseldorf, Germany.
Böcking
Alfred
A
Kazimirek
Marietta
M
Onofre
Alexandre Sherlley Casimiro
AS
Gabbert
Helmut Erich
HE
Kappes
Rainer
R
Gerharz
Claus Dieter
CD
Grote
Hans Juergen
HJ
D025601:Adenomatous Polyposis Coli Protein / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001980:Bronchi / Q000378:metabolism*; D001999:Bronchoscopy; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D015331:Cohort Studies; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013447:Sulfites / Q000494:pharmacology; D013696:Temperature; D025521:Tumor Suppressor Proteins / Q000235:genetics
D025601:Adenomatous Polyposis Coli Protein; D019941:Cyclin-Dependent Kinase Inhibitor p16; D017931:DNA Primers; C411762:RASSF1 protein, human; D018168:Receptors, Retinoic Acid; D013447:Sulfites; D025521:Tumor Suppressor Proteins; C082925:retinoic acid receptor beta