Detection of gene promoter hypermethylation in fine needle washings from breast lesions.
OBJECTIVE
Fine needle aspiration (FNA) is used widely in diagnostic assessment of breast lesions. However, cytomorphological evaluation depends heavily on the proficiency of cytopathologists. Because epigenetic alterations are frequent and specific enough to potentially augment the accuracy of malignant disease detection, we tested whether hypermethylation analysis of a panel of genes would distinguish benign from malignant breast FNA washings.


METHODS
FNA washings were collected from 123 female patients harboring suspicious mammary lesions. Sodium bisulfite-modified DNA was amplified by methyl-specific PCR (MSP) for CDH1, GSTP1, BRCA1, and RARbeta to detect gene promoter CpG island methylation. Paired samples of 27 breast cancer tissue and 7 fibroadenomas and 12 samples of normal breast tissue, collected postoperatively, were also analyzed. MSP results were compared with conventional cytomorphological diagnosis.


RESULTS
FNAs were cytomorphologically diagnosed as benign (25 cases), malignant (76 cases), suspicious for malignancy (6 cases), and unsatisfactory (16 cases). Percentages of methylated CDH1, GSTP1, BRCA1, and RARbeta in FNA washings were 60, 52, 32, and 16%, and 65.8, 57.9, 39.5, and 34.2% for benign and malignant lesions, respectively. These differences did not reach statistical significance. In all of the paired benign lesions tested, there was absolute concordance. Sixty-seven percent (18 of 27) of FNA washings displayed hypermethylation patterns identical to malignant paired tissue. No methylation was found in the normal breast samples for any of the genes.


CONCLUSIONS
Detection of gene hypermethylation in FNA washings by MSP analysis is feasible, but the selected gene panel does not discriminate between benign and malignant breast lesions.
Jerónimo
Carmen
C
Department of Genetics, Portuguese Oncology Institute-Porto, 4200-072 Porto, Portugal. cjeronimo@hotmail.com
Costa
Isabel
I
Martins
M Conceição
MC
Monteiro
Paula
P
Lisboa
Susana
S
Palmeira
Carlos
C
Henrique
Rui
R
Teixeira
Manuel R
MR
Lopes
Carlos
C
D044963:Biopsy, Fine-Needle; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000175:diagnosis / Q000235:genetics*; D018899:CpG Islands; D019175:DNA Methylation; D005260:Female; D020868:Gene Silencing; D019398:Genes, BRCA1; D006801:Humans; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000235:genetics; D013447:Sulfites / Q000494:pharmacology
D018168:Receptors, Retinoic Acid; D013447:Sulfites; C082925:retinoic acid receptor beta; C009279:sodium bisulfite