Comparison of Immunohistochemical 2 (+) HER2 Gene Status with SISH in Invasive Breast Carcinoma

Year 2025, Volume: 15 Issue: 4, 338 - 345

Alper Sayiner , Hatice Karaman , Fatma Şenel , Arzu Tasdemir , Merve Doğan , İpek Özer

Abstract

Background: The aim of this study is to evaluate the HER2 (c-erbB-2) gene status in patients with invasive breast cancer who have received an equivocal (2+) score during immunohistochemical (IHC) testing. The study employs the Silver DNA in Situ Hybridization (SISH) technique for this estimation and further investigates its association with various clinicopathological variables.
Materials and methods: This study is a retrospective analysis consisting of 133 formalin-fixed paraffin-embedded tissue blocks from female patients diagnosed with invasive breast carcinoma and having an equivocal (2+) HER2 IHC score. HER2 DNA amplification in all cases was studied using the SISH technique. ER, PR, and Ki-67 stainings were evaluated by the IHC method.
Results: From a total of 442 invasive breast carcinoma cases, 224 (50.70%) were found to be HER2 negative, 85 (19.20%) were HER2 3(+), and 133 (30.10%) had an equivocal 2+ HER2 score as determined by IHC. Among these 133 cases, HER-2 gene amplification was confirmed in 29.30% (39/133) by SISH. A statistically significant association was found between SISH status and Ki-67 index (P=0.04). Additionally, for cases with negative SISH results, a positive correlation was observed between the estrogen receptor (ER) and progesterone receptor (PR) statuses (P <0.01).
Conclusion: The study underscores the importance of employing genetic tests like SISH to confirm the HER-2 gene status in cases with an equivocal 2+ IHC score. The SISH technique is emphasized as easy, time-efficient, cost-effective, and a reliable method for such confirmatory tests.

Keywords

Breast carcinoma , HER2 , Immunohistochemistry Silver in situ hybridization (SISH)

References

• Lakhani SR, Ellis IO, Schnitt SJ, Tan PH, van de Vijver MJ, eds. WHO Classification of Tumours of the Breast. 4th ed. Lyon, France: International Agency for Research on Cancer; 2012. (WHO Classification of Tumours; vol 4).
• Tavassoli FA, Devilee P, eds. Pathology and Genetics of Tumours of the Breast and Female Genital Organs. 3rd ed. Lyon, France: IARC Press; 2003. (WHO Classification of Tumours; vol 3).
• Ross JS, Fletcher JA, Linette GP, Stec J, Clark E, Ayers M, et al. The Her-2/neu gene and protein in breast cancer 2003: Biomarker and target of therapy. Oncologist. 2003;8(4):307-25. doi:10.1634/theoncologist.8-4-307
• Allred DC. Evaluating estrogen receptor-alpha, progesterone receptor, and HER2 in breast cancer. Mod Pathol. 2010;23(Suppl 2):S52–9. doi:10.1038/modpathol.2010.55
• Mitri Z, Constantine T, O'Regan R. The HER2 receptor in breast cancer: pathophysiology, clinical use, and new advances in therapy. Chemother Res Pract. 2012;2012:743193. doi:10.1155/2012/743193
• Dieci MV, Barbieri E, Bettelli S, et al. Predictors of human epidermal growth factor receptor 2 fluorescence in-situ hybridisation amplification in immunohistochemistry score 2+ infiltrating breast cancer. J Clin Pathol. 2012;65(6):503–6. doi:10.1136/jclinpath-2011-200643
• Musa ZA, Qasim BJ, Wahab A, Shaikhly A. Evaluation of immunohistochemistry-equivocal (2+) HER2 gene status in invasive breast cancer by silver DNA in situ hybridization (SISH) and its association with clinicopathological variables. Iran J Pathol. 2017;12(1):9-19. PMCID: PMC5938719.
• Hoda RS, Brogi E, Xu J, et al. Impact of the 2018 ASCO/CAP HER2 guideline updates on HER2 assessment in breast cancer with equivocal HER2 immunohistochemistry results with focus on cases with HER2/CEP17 ratio <2.0 and average HER2 copy number ≥4.0 and <6.0. Arch Pathol Lab Med. 2020;144(5):597–601. doi:10.5858/arpa.2019-0307-OA
• Griffin BB, Pincus JL, Siziopikou KP, Blanco LZ. Double-equivocal HER2 invasive breast carcinomas: Institutional experience and review of literature. Arch Pathol Lab Med. 2018;142(12):1511–6. doi:10.5858/arpa.2017-0265-RA
• Ahn S, Woo JW, Lee K, Park SY. HER2 status in breast cancer: Changes in guidelines and complicating factors for interpretation. Pathol Transl Med. 2020;54(1):34–44. doi:10.4132/jptm.2019.11.03
• Wolff AC, Hammond ME, Schwartz JN, et al. American Society of Clinical Oncology/College of American Pathologists guideline recommendations for human epidermal growth factor receptor 2 testing in breast cancer. Arch Pathol Lab Med. 2007;131(1):18–43. doi:10.5858/2007-131-18-ASOCCO
• Wolff AC, Hammond ME, Allison KH, Harvey BE, Mangu PB, Bartlett JM, et al. Human epidermal growth factor receptor 2 testing in breast cancer: ASCO/CAP clinical practice guideline focused update. Arch Pathol Lab Med. 2018;142(11):1364–82. doi:10.1200/JCO.2018.77.8738
• Dietel M, Ellis IO, Höfler H, et al. Comparison of automated silver enhanced in situ hybridisation (SISH) and fluorescence ISH (FISH) for the validation of HER2 gene status in breast carcinoma according to ASCO/CAP guidelines. Virchows Arch. 2007;451(1):19–25. doi:10.1007/s00428-007-0424-5
• Kang J, Kwon GY, Lee YH, Gong G. Comparison of silver-enhanced in situ hybridization and fluorescence in situ hybridization for HER2 gene status in breast carcinomas. J Breast Cancer. 2009;12(3):235–40. doi:10.4048/jbc.2009.12.4.235
• Lee AH, Key HP, Bell JA, Shaaban AM, Ellis IO. Breast carcinomas with borderline (2+) HER2 immunohistochemistry: Percentage of cells with complete membrane staining for HER2 and the frequency of HER2 amplification. J Clin Pathol. 2011;64(6):490–2. doi:10.1136/jcp.2011.089177
• Chibon F, Mascarel I, Sierankowski G, de Mascarel I, MacGrogan G, Coindre JM. Prediction of HER2 gene status in Her2 2+ invasive breast cancer: A study of 108 cases comparing ASCO/CAP and FDA recommendations. Mod Pathol. 2009;22(3):403–9. doi:10.1038/modpathol.2008.195
• Papouchado BG, Myles J, Lloyd RV, et al. Silver in situ hybridization (SISH) for determination of HER2 gene status in breast carcinoma: Comparison with FISH and assessment of interobserver reproducibility. Am J Surg Pathol. 2010;34(6):767–76. doi:10.1097/PAS.0b013e3181d96231
• Carbone A, Botti G, Gloghini A, et al. Delineation of HER2 gene status in breast carcinoma by silver in situ hybridization is reproducible among laboratories and pathologists. J Mol Diagn. 2008;10(6):527–36. doi:10.2353/jmoldx.2008.080052
• Slamon DJ, Clark GM, Wong SG, Levin WJ, Ullrich A, McGuire WL. Human breast cancer: Correlation of relapse and survival with amplification of the HER-2/neu oncogene. Science. 1987;235(4785):177–82. doi:10.1126/science.3798106
• Paik S, Hazan R, Fisher ER, Sass RE, Fisher B, Redmond C, et al. Prognostic significance of erbB-2 protein overexpression in primary breast cancer. J Clin Oncol. 1990;8(1):103–12. doi:10.1200/JCO.1990.8.1.103
• Carr JA, Havstad S, Zarbo RJ, Divine G, Mackowiak P, Velanovich V. The association of HER-2/neu amplification with breast cancer recurrence. Arch Surg. 2000;135(12):1469–74.
• Ji Y, Sheng L, Du X, Qiu G, Chen B, Wang X. Clinicopathological variables predicting HER-2 gene status in immunohistochemistry-equivocal (2+) invasive breast cancer. J Thorac Dis. 2014;6(6):896–904.