Evaluation of breast cancer metastases in pleural effusions by molecular biology techniques.

The aim of this study was to evaluate the presence of allelic loss in chromosomal regions previously described as exhibiting loss of heterozygosity (LOH) during breast carcinogenesis, in pleural effusions of breast cancer patients. LOH was analyzed in three loci (1p32, 7q31, and 17q21). We studied 41 samples of pleural effusions from breast cancer patients (24 positive for neoplastic cells, 14 suspected, and 3 negative cases) and breast tissues from the patients (primary tumors and nonneoplastic adjacent tissue). DNA was extracted from pleural effusions, primary tumor, and adjacent normal tissue. LOH was evaluated by polymerase chain reaction assay and was observed in 38% of pleural effusions positive for neoplastic cells, and in 36% of suspected cases where morphology only did not allow the diagnosis of malignancy. We conclude that LOH analysis in pleural effusions of breast cancer patients is able to identify metastases in cases where morphologic analysis becomes difficult.