Fine Needle Aspiration May Shed Breast Cells into Peripheral Blood as Determined by RT-PCR

OBJECTIVE: A diagnostic test applying reverse-transcriptase chain reaction (RT-PCR) assay targeted against cytokeratin 19 (CK19), cytokeratin 20 (CK20) and the beta-subunit of human chorionic gonadotropin (beta-hCG) mRNAs was used to evaluate the impact of fine needle aspiration (FNA) on breast cell shedding into peripheral blood. METHODS: The sensitivity of this assay was based on the different degree of admix of MCF-7 breast cancer cell line with HL-60 leukemic cell line. For blood samples of 24 cases with benign breast diseases and 20 cases with malignant ones, 5 ml of peripheral blood was drawn before and within 10 min after puncture. Total RNA was extracted from peripheral blood mononuclear (PBMN) cells; beta-actin was used to assess the quality of cDNA. RT-PCR products were run in ethidium bromide gel and observed under ultraviolet. RT-PCR products for beta-hCG were digested with Sty I endonuclease to confirm the specificity. RESULTS: The sensitivity of RT-PCR assay was 1 MCF-7 cell in 10(5) HL-60 cells for CK19 and CK20, and 1 in 10(6) for beta-hCG. For 24 benign cases, none of the pre- FNA samples was positive for CK20 and beta-hCG, and 3 cases (12.5%) were positive for CK19. As for 20 malignant cases, 1 pre-FNA sample was positive for all three markers and 2 other samples were positive for CK19. After aspiration, 3/21 benign cases and 1/17 malignant case with pre-FNA negative signals became positive for CK19, while 3/19 malignant cases with pre-FNA negative signals were converted to a positive result for CK20 and beta-hCG. Of 6 pre-FNA positive cases, all cases remained positive for the respective marker. CONCLUSION: FNA to breast tumor may cause hematogenous dissemination of breast cells.