Correlation and comparison of immunohistochemistry for HER2/neu, using the antibody <i>SP3</i> and chromogenic <i>in situ</i> hybridization in breast carcinomas samples

Wolf, Franciele F.; Bublitz, Giuliano S.; Frigeri, Henrique R.

doi:10.5935/1676-2444.20150063

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PATHOLOGY • J. Bras. Patol. Med. Lab. 51 (6) • Dec 2015 • https://doi.org/10.5935/1676-2444.20150063 copy

Correlation and comparison of immunohistochemistry for HER2/neu, using the antibody SP3 and chromogenic in situ hybridization in breast carcinomas samples

Correlação e comparação de imuno-histoquímica para HER2/neu, utilizando o anticorpo SP3 com a hibridização in situ cromógena em amostras de carcinomas mamários

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Introduction:

Advances in the field of molecular biology have provided the differentiation of molecular subtypes of breast tumors, providing better prognosis and important tools for the treatment of patients with breast cancer. Among these subtypes, the changes in the human epidermal growth factor receptor 2 gene (HER2/neu), increase its copy number and generating HER2 protein amplification. Studies show that patients with breast cancer HER2/neu amplified tend to relapse earlier and have shorter survival time, the monoclonal antibody Trastuzumab is the therapy indicated. The eligibility of patients for therapy is initially made by the immunohistochemistry (IHC) technique, which evaluates the expression level of the HER2 protein. After this evaluation, the cases with equivocal diagnosis (score 2+), are referred to a more accurate technique, the chromogenic in situ hybridization (CISH).

Objective:

To analyze the sensitivity and specificity of the antibody SP3, and determine their level of agreement with the CISH technique.

Material and methods:

Retrospective study in the database of the anatomy-pathology laboratory, in CISH tests reports for HER2/neu.

Conclusion:

The results revealed that clone SP3 showed 100% specificity and 92% sensitivity. IHC reveals variability in its results; however, it is known that the technique is an important tool in the daily routine of laboratories, contributing to the initial screening of patients with breast cancer, which later showed satisfactory results when compared with the CISH technique.

Key words:
breast cancer; in situ hybridization; immunohistochemistry

IHC score	Criteria	%C	%CWAF/C
0 (negative)	No immunoreactivity or immunoreac-tivity in less than 10% tumor cells	~60%	0%-3%
1+ (negative)	Weak immunoreactivity in more than 10% of tumor cells, but only part of the membrane is positive	~10%	0%-7%
2+ (equivocal)^# # The panel of expert recommended to test the doubtful cases to gene amplification by FISH;	Weak to moderate complete membrane immunoreactivity in more than 10% of the tumor cells or intense circumferential membrane staining in less than 30% cells	~5%-10%	25%-35%
3+ (positive)	More than 30% of the tumor cells should show intense and uniform staining of the circumferential membrane. A homogeneous pattern must be present	~15%-20%	95%^## ## The expert panel increased the fraction of cells with membrane staining from 10% to 30%, to increase the correlation with gene amplification by FISH. According to the panel, cancer with 3+ by IHC result should show gene amplification in at least 95% of cases.

ISH result	Critera	Comments
Positive for amplification	> 6 copies of the gene or > 2.2 ratio	> 6 copies of the gene may be present in a ratio < 2.2, if the polysomy is present. Besides the relation, the number of genes and number of 17 chromosome must be provided when they are determined as part of the test
Equivocal for amplification	4 to 6 gene or 1.8 to 2.2 ratio^# # patients with ratio 2.0 or higher were eligible for Herceptin® test.	The guidelines suggest counting additional cells by FISH, retest, or performing IHC
Negative for amplification	< 4 gene or < 1.8 ratio

Score IHC SP3	CISH positive	CISH negative
0/1+	3	47
2+	8	3
3+	37	0
Total	48	50

SP3 scores	CISH positive	CISH negative	Total
SP3 3+	37	0	37
SP3 0/1+	3	47	50
Total	40	47	87

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E-mail: jbpml@sbpc.org.br

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[1] Mailing address: Franciele Ferreira Wolf , Rua Mário Lobo, 61, sala 606, Edifício Terraço Center; CEP 89201-330; Joinville-SC, Brazil; Phone: +55 (47) 3422 9607; Fax: +55 (47) 3422 8169/3433-9499; e-mail: fran_bios@hotmail.com.