GastricHer2

HER2 NEU GASTRIC/ GASTROESOPHAGEAL JUNCTION
SEMI-QUANTITATIVE MANUAL IMMUNOHISTOCHEMISTRY

INTERPRETATION:
NEGATIVE (SCORE 0)
NEGATIVE (SCORE 1+)
EQUIVOCAL (SCORE 2+)
POSITIVE (SCORE 3+)

PERFORMED ON (Case #, Block):
Reference range for Her-2/neu IHC:
Positive: 3+
Equivocal: 2+
Negative: 0, 1+

Review of the slide confirms the presence of invasive carcinoma. The criteria for interpreting HER2 IHC on gastric carcinoma differ significantly from the breast cancer criteria. The gastric carcinomas are scored using manual semi-quantitative analysis as stipulated by the criteria in which the percentages of cells are analyzed. The criteria for HER2 overexpression differ when interpreting biopsy and resection specimens due to increased heterogeneity of HER2 expression in gastric and gastroesophageal junction carcinomas. These findings are summarized as a narrative and in the table below (table best viewed as PDF report file).
Surgical specimens:
Score of 0 is no reactivity or membranous reactivity (staining) in <10% of invasive tumor cells. Score of 1+ is faint/barely perceptible membranous reactivity (staining) in > or =10% of invasive tumor cells; cells are reactive (stained) only in part of their membrane. Score of 2+ is weak to moderate complete, basolateral or lateral membranous reactivity (staining) in > or =10% of invasive tumor cells. Score of 3+ is strong complete, basolateral or lateral membranous reactivity (staining) in > or =10% of invasive tumor cells.
Biopsy specimens:
Score of 0 is no reactivity or no membranous reactivity (staining) in less than 5 clustered tumor cells. Score of 1+ is tumor cell clusters (greater than or equal to 5 cells) with a faint/barely perceptible membranous reactivity (staining) regardless of percentage of invasive tumor cells stained. Score of 2+ is tumor cell clusters (greater than or equal to 5 cells) with a weak to moderate complete, basolateral or lateral membranous reactivity (staining) regardless of percentage of invasive tumor cells stained. Score of 3+ is tumor cell clusters (greater than or equal to 5 cells) with a strong complete, basolateral or lateral membranous reactivity (staining) regardless of percentage of invasive tumor cells stained.
The performance characteristics of this test were validated by UF Pathology Laboratories.

HER2
Interpretation

Staining
Intensity Score

Surgical resections

Biopsies

Negative

0

No reactivity or membranous reactivity in <10% of tumor cells

No reactivity or membranous reactivity in <5 clustered tumor cells

Negative*
(*reflex FISH)

1+ (40x)

Faint/barely perceptible membranous reactivity in > 10% of tumor cells; cells are reactive only in part of their membrane

Tumor cell cluster (>5 cells) with a faint/barely perceptible membranous reactivity irrespective of percentage of tumor cells stained.

Equivocal*
(*reflex FISH)

2+ (10 - 20x)

Weak to moderate complete, basolateral or lateral membranous reactivity in >10% of tumor cells

Tumor cell clusters (>5 cells) with a weak to moderate complete, basolateral or lateral membranous reactivity irrespective or percentage of tumor cells stained.

Positive

3+ (2.5 – 5x)

Strong complete, basolateral or lateral membranous reactivity in > 10% of tumor cells

Tumor cell clusters (>5 cells) with a strong complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained.

REFERENCE:
Hofmann M, Stoss O, Shi D, Buttner R, van de Vijver M, Kim W, et al. Assessment of a HER2 scoring system for gastric cancer: results from a validation study. Histopath 2008; 52:797-805.
Ruschoff J. HER2 diagnostics in gastric cancer-guideline validation and development of standardized immunohistochemical testing. Virch Arch 2010; 457:299

HER2 Interpretation	Staining Intensity Score	Surgical resections	Biopsies
Negative	0	No reactivity or membranous reactivity in <10% of tumor cells	No reactivity or membranous reactivity in <5 clustered tumor cells
Negative* (*reflex FISH)	1+ (40x)	Faint/barely perceptible membranous reactivity in > 10% of tumor cells; cells are reactive only in part of their membrane	Tumor cell cluster (>5 cells) with a faint/barely perceptible membranous reactivity irrespective of percentage of tumor cells stained.
Equivocal* (*reflex FISH)	2+ (10 - 20x)	Weak to moderate complete, basolateral or lateral membranous reactivity in >10% of tumor cells	Tumor cell clusters (>5 cells) with a weak to moderate complete, basolateral or lateral membranous reactivity irrespective or percentage of tumor cells stained.
Positive	3+ (2.5 – 5x)	Strong complete, basolateral or lateral membranous reactivity in > 10% of tumor cells	Tumor cell clusters (>5 cells) with a strong complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained.