Fine needle aspiration may shed breast cells into peripheral blood as determined by RT-PCR

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.

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.

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.

FNA to breast tumor may cause hematogenous dissemination of breast cells.