Comparison of a novel molecular assay with touch imprint and permanent histology of sentinel lymph nodes in early-stage breast cancer.

Abstract

642 Background: Current intraoperative assay of the sentinel lymph nodes (SLN) either by touch imprint or frozen section has high false-negative rates. We aimed to study validity of a novel reverse transcriptase-polymerase chain reaction (RT-PCR) assay compared to intraoperative touch preps as well as final histology. Methods: Pts with BrCa underwent SLN Mapping (M). Alternate slices of the SLNs were examined for mammoglobin and cytokeratin 19 (CK19) by RT-PCR assay, with the remainder of the SLNs processed and evaluated pathologically with four H&E and one CK immunostain. Results: Seventy-eight pts were studies. Nine (11.5%) DCIS, 57 (73.1%) T1, 11 (14.1%) T2 and 1 (1.3%) had T3 tumor. Overall nodal metastasis was 25% with 4 pts having positive micrometastasis (0.2-2 mm). In the included 69 pts (excluding DCIS), sensitivity of RT-PCR was 81.3% compared to 50% for touch prep. RT-PCR carried a negative predictive value of 94.5% (52/55 pts) compared to 86.8% (53/61) with touch preps. RT-PCR identified one p...