FISH Analysis of TOP2A and HER-2 Aberrations in Female Breast Carcinoma on Archived Material: Egyptian NCI Experience.

BACKGROUND: HER-2 and TOP2A genes are considered of great importance in breast cancer. Their copy number variability has been proposed to be a marker for the degree of chromosomal instability. Owing to the close proximity of TOP2A gene to HER-2 gene chromosome 17, TOP2A status is believed to affect therapeutic plan. The percentage of TOP2A aberrations is greatly variable among different studies.

AIM OF WORK: Is to investigate the relation between TOP2A and HER-2 gene amplification using fluorescence in situ hybridization technique.

MATERIALS AND METHODS: Archival blocks of 112 breast cancer Egyptian female patients were retrieved from the pathology department at NCI, Cairo University were retrieved and investigated using fluorescence in situ hybridization technique for TOP2A and HER-2 gene assessment. In addition, correlation with some clinicopathologic parameters was done.

RESULTS: HER-2 gene amplification was encountered in about 33% of cases. TOP2A gene amplification and deletion were detected in 23.9% and 2.8% of studied cases. Moderate agreement was obtained between results of HER-2 gene and TOP2A gene amplification.

CONCLUSIONS: HER-2 and TOP2A genes amplification are 2 separate genetic yet closely related events in breast cancer. Polysomy of chromosome 17 is proposed to be an early event in occurrence of TOP2A gene amplification. Further studies regarding effect of TOP2A gene in response to anthracyclines in Egyptian population should be planned for to establish its role in therapeutic planning.