Immunocytochemical Detection of HER2 in Urine Cytology in Previously Papanicolaou-Stained Slides Is Comparable to Correspondent Urothelial Carcinoma Tissue Samples
Yaxia Zhang, Soraya Rodriguez, Carmen Gomez-Fernandez, Monica Garcia, Parvin Ganjei-Azar, Gustavo Fernandez-Castro, Merce Jorda. University of Miami, Miller School of Medicine-Jackson Memorial Hospital, Miami, FL
Background: Reported rates of HER2 overexpression in urothelial carcinoma of the urinary bladder (UCB) varies widely from 10 to 80%. Majority of studies have been performed on tissue or cell-block samples with little information available on the reproducibility of the test in previously Papanicolaou-stained slides. Detection of HER2 may become routine in UCB patients, since Trastuzumab combined chemotherapy has proven to be a feasible treatment in advanced or metastatic UCB patients in a multicenter Phase II NCI trial. Preferably, HER2 testing is performed on tissue samples, however, if tissue is limited or not available, knowledge of reproducibility of the test in stored cytology samples is desirable. The aim of this study was to compare HER2 expression by immunocytochemistry (ICC) in previously Papanicolaou-stained slides with corresponding tissue samples in patients with UCB.
Design: Thirty-six urine cytology slides and corresponding tissue samples from patient with high-grade UCB were tested for HER2 by ICC and immunohistochemistry, respectively. C-erbB-2 polyclonal antibody (Dako) was tested on alcohol-fixed, previously Papanicolaou-stained slides and in tissue sections, using the L-SAB detection system. In tissue sections, criteria used for a positive result was based on the score system currently available for breast carcinoma. Moderate to strong homogeneous membrane staining (3+) over 30% of tumor cells in the tissue sections was considered positive. In cytology slides, a positive result was recorded when more than 30% of isolated tumor cells showed strong homogeneous membrane staining.
Results: HER2 overexpression was detected in 23 of 36 (64%) urine cytology samples and in 28 of 36 (78%) histology samples. In 20 cases, HER2 was detected in both, urine and correspondent tissue. Of the eight equivocal (2) and negative (6) cases on tissue, 3 were positive in urine slides. Positive predictive value for the detection of HER2 by ICC in urine samples is 87%.
Conclusions: Detection of HER2 over-expression in urine cytology by ICC positively correlates with tissue section results. Previously Papanicolaou-stained slides from urine samples can be used for HER2 ICC detection when tissue sample is scarce or not available.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 75, Tuesday Morning