[663] Image Cytometric HER2 in Gastric Carcinoma – Is a New Algorithm Needed?

Bradley Feiger, Claudia Ormenisan, Diane Lawson, Jason Wang, Cynthia Cohen. Emory University, Atlanta, GA

Background: Algorithms for quantitation of HER2 immunohistochemistry were developed for breast carcinoma, where the membranous stain must be entirely around the cell membrane. For gastric carcinoma, although assessment of intensity of immunostain (0-3) is similar, the site and percent of stain differs by lacking the requirement of entire cell membrane positivity (complete, basolateral or lateral membranous reactivity is sufficient for a positive result). We quantitated HER2 in gastric cancer specimens visually and by image cytometry, comparing results, and where available, with fluorescence in situ hybridization(FISH). The goal was to assess whether lack of concordance among results, might suggest a requirement for changing the image cytometric algorithm.
Design: All gastric carcinoma biopsies, resections and cell blocks studied for HER2 expression/amplification in the past 2 years were included. Immunostain intensity, percent and score 0-3+ (0, 1+ negative, 2+ equivocal, 3+ positive), were evaluated visually, and by image cytometry, with the ACIS score (DAKO) 0-3(0, 1 negative, 2 equivocal, 3 positive). FISH(<1.8 negative,>1.8-<2.2 equivocal,>2.2 amplified) was performed on all specimens with scores 2 and 3 by image cytometry.Results were compared.
Results: 41 specimens were studied, including 23(56%) biopsies, 13(32%) resections and 5(12%) cell blocks. 29(71%) were primary gastric, esophageal or gastroesophageal junction adenocarcinoma; 12(29%) were metastatic; 2(5%) were well, 8(20%) moderately, and 31(75%) poorly differentiated.

HER 2	Visual No (%)	Image Cytometry No (%)	FISH No (%)	p value
Negative(0,1)	31 (75)	32 (78)	3 (27)	<0.001
Equivocal(2)	2 (5)	2 (5)	1 (9)	0.85
Positive/Amplified(3)	8 (20)	7 (17)	7 (64)	0.87
Total	41	41	11

Specimen Type (No)	HER2 Positive/Amplified No(%)	p value
Resection (13)	2 (15.4)	0.61
Biopsy (23)	4 (17.4)
Cell Block (5)	2 (40)
Tumor Type
Primary (29)	5 (17)	0.73
Metastatic (12)	3 (25)
Differentiation
Well (2)	0 (0)	0.07
Moderate (8)	1 (12.5)
Poor (31)	7 (22.6)
Total (41)	8 (19.5)

Conclusions: Despite different recommendations for interpretation of HER2 in gastric vs. breast cancer, equivocal and positive/amplified results visually, and by image cytometry, and where FISH was performed, are similar.
This concordance is noted for biopsy, resection and cell block specimens, for primary vs. metastatic, and for moderately vs. poorly differentiated carcinoma, although HER2 positivity/amplification is most frequent with poor differentiation.
There appears to be no need for the HER2 image cytometric algorithm used for breast cancer, to be changed when used for assessment of gastric cancers.
Category: Gastrointestinal

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 52, Tuesday Afternoon