International Journal of Hematology and Oncology 2019, Vol 29, Num 2 Page(s): 001-008
COMPARATIVE ANALYSIS OF HER-2/NEU AMPLIFICATION, OVEREXPRESSION AND POLYSOMY 17 IN PATIENTS WITH METASTATIC BREAST CANCER

Tahsin YAKUT1, Mutlu DEMİRAY2, Tuna GÜLTEN1, İlker ERCAN3, Mustafa HATİPOĞLU1, Barbaros YİĞİT1, Şahsene TOLUNAY4

1Uludag University Medical Faculty, Medical Genetics Department, BURSA
2Uludag University Medical Faculty, Oncology Department, BURSA
3Uludag University Medical Faculty, Biostatistics Department, BURSA
4Uludag University Medical Faculty, Pathology Department, BURSA

Keywords: HER-2/neu, Metastatic breast cancers, IHC, FISH
Amplification or overexpression of HER-2/neu oncogene is associated with poor prognosis and has been correlated with the response to trastuzumab treatment. Chromosomal copy number changes of chromosome 17 occurs in breast cancers and effect the copy number of HER-2/neu gene and consequently IHC score relatively. The aim of this study was to investigate the contribution of chromosome 17 polysomy to positive HER-2/neu immunostaining independent of HER-2/neu amplification using dual-color FISH technique on the paraffin-embedded tissues of metastatic breast cancers. Paraffin-embedded speciment of 32 metastatic breast cancer cases were analysed using dual-color FISH probes specific to HER-2/neu gene and chromosome 17. Results showed significant association between the cases with IHC 2+ and polysomy 17 (p=0.011), and IHC 3+ and HER-2/neu amplification (p=0.023). In conclusion, increased HER-2/neu gene copy number in accordance with polysomy 17 might lead to a strong protein overexpression in the metastatic breast cancer. Therefore FISH technique may also be more sensitive interpretation tool in cases with polysomy 17.