[1080] Immunohistochemical Expression of HER2 in Urothelial Carcinoma of the Bladder (UC): Comparison of the Breast Cancer (BC) and Gastric Cancer (GC) HER2 Scoring Systems

Bing Zhu, Xiaoqi Lin, Stephen Rohan, Minghao Zhong, Rajen Goyal, Elizabeth Gersbach, Ximing Yang. Northwestern University, Chicago

Background: Immunohistochemistry (IHC) for HER2 expression is important for determining prognosis and treatment in several types of cancer. HER2 protein expression has been described in UC, ranging from 5 to 98%. The criteria for scoring HER2 IHC expression in BC and GC are well established but differ significantly. In this study, we compare HER2 IHC expression using the GC and BC scoring systems in UC of various grades and micropapillary UC (MPUC) of different stages.
Design: 20 MPUC, 57 high grade UC (HGUC) and 21 low grade UC (LGUC) were evaluated. IHC for HER2 was performed on paraffin-embedded tissues and expression was evaluated using the BC and GC scoring systems. The BC system requires at least 30% tumor cells with complete membrane staining, and is scored as 0 (absent staining), 1+ (faint intensity), 2+ (moderate intensity), and 3+ (strong intensity). The GC system requires at least 10% tumor cells with basolateral staining, and is scored as 0 (absent staining), 1+ (faint intensity), 2+ (moderate intensity), and 3+ (strong intensity).
Results: See tables.

Table1. HER2 expression in MPUC, HGUC and LGUC

Subtypes	BC System		GC System
	Mean±SD	T test	Mean±SD	T test
MPUC (n=20)	1.65±0.81	*0.668, **0.049	2.15±1.09	*0.069, **0.002
HGUC (n=57)	1.54±1.25	^0.091	1.60±1.27	^0.063
LGUC (n=21)	1.05±1.07		1.05±1.07

*: MPUC vs. HGUC. **: MPUC vs LGUC. ^: HGUC vs. LGUC

Table2. HER2 expression in different stages of MPUC

Stages	BC System		GC System
	Mean±SD	T test	Mean±SD	T test
T1 (n=4)	0.75±0.5	*0.059,**0.005	1.00±0.81	*0.16, **0.003
T2 (n=8)	1.63±0.93	^0.183	1.88±1.13	^0.025
T3 (n=8)	2.13±0.35		3.00±0.00

*:T1 vs. T2 **: T1 vs. T3. ^: T2 vs. T3


Conclusions: 1. Regardless of the scoring system used, there was a trend towards higher expression of HER2 in HGUC compared to LGUC, and in MPUC compared to both HGUC and LGUC. In addition, overexpression of HER2 is seen in higher stage MPUC. These data suggest that HER2 overexpression may be prognostically significant.
2. The GC scoring system appears to correlate better with tumor stage grade than the BC system. The true prognostic and therapeutic relevance of this finding, however, will be dependent upon further studies comparing IHC scoring systems in conjunction with gene amplification studies and the potential clinical trial of HER2-target therapy.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 136, Wednesday Afternoon