Turkish Journal of Pathology

Türk Patoloji Dergisi

Turkish Journal of Pathology

Turkish Journal of Pathology

2014, Vol 30, Num, 2     (Pages: 087-093)

In Situ Hybridization Analysis of Invasive Breast Carcinomas with Immunohistochemically Negative Her-2 Status (A National Multicenter Study)

Sıtkı TUZLALI 1, Ekrem YAVUZ 1, Tülay CANDA 2, Merih GÜRAY 2, Melin Özgün GEÇER 3, Yurdanur SÜLLÜ 4, Cem SEZER 5, Dinç SÜREN 5, Serpil DİZBAY SAK 6, Zerrin CALAY 7, Şennur İLVAN 7, Suzan ZORLUDEMİR 8, Melek ERGİN 8, Fatma Şeyda KARAVELİ 9, Elif PEŞTERELİ 9, Fatih ÖZDENER 10, Kasım ÜSTÜNDAĞ 10

1 Departments of Pathology, 1İstanbul University, İstanbul Faculty of Medicine, İSTANBUL, TURKEY
2 Dokuz Eylül University, Faculty of Medicine, İZMİR, TURKEY
3 Lütfi Kırdar Kartal Training and Research Hospital, İSTANBUL,TURKEY
4 Ondokuz Mayıs University, Faculty of Medicine, SAMSUN, TURKEY
5 Antalya Training and Research Hospital, ANTALYA, TURKEY
6 Ankara University, Faculty of Medicine, ANKARA, TURKEY
7 İstanbul University, Cerrahpaşa Faculty of Medicine, İSTANBUL, TURKEY
8 Çukurova University, Faculty of Medicine, ADANA, TURKEY
9 Akdeniz University, Faculty of Medicine, ANTALYA, TURKEY
10 Roche Müstahzarlari San. A.S., TURKEY

DOI: 10.5146/tjpath.2014.01240
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Objective: The aim of this study was to determine the rate of Her-2 gene amplification in breast cancer cases with a previous negative Her-2 result as determined by immunohistochemistry (score 0 or 1).

Material and Method: 552 cases of invasive breast carcinoma were assessed with the contribution of 9 centers. Previous immunohistochemistry score was either 0 or 1+ in all cases. These cases were re-tested by Her-2 silver in situ hybridization in the central laboratory. Her-2 gene amplification was defined as Her-2/CEP 17 ratio of more than 2.2. Cases with a ratio between 1.8 and 2.0 were defined as equivocal and cases with a ratio of less than 1.8 were defined as negative.

Results: Re-testing of the 552 cases with silver in situ hybridization showed a total of 22 cases with Her-2 gene amplification, of which 11 (3.2%) were found to be score 0, and 11 were found to be score 1+ (5.3%) by immunohistochemistry previously. Her-2 gene amplification rate of cases (score 0 and 1+) ranged from 0% to 10.48% among the centers. Polysomy was found in 28 (8.1%) of the score 0 cases and 25 (12.1%) among the score 1+ cases. Five (9.4%) of the cases with polysomy were found to be amplified, and 48 (90.6%) were not.

Conclusion: The results of the study show that a group of cases (3.98%) with a potential to benefit from anti-Her-2 therapy may be missed with the immunohistochemical method. This indicates the importance of quality assurance, especially in central laboratories with many breast cancer cases in daily practice.

Keywords : In situ hybridization, Immunohistochemistry, Breast neoplasms, Her-2, Quality assurance