Recent clinical studies have shown that TOPOIIα gene amplification is a more specific predictor than TOPOIIα expression assessed by immunohistochemistry and HER-2 gene amplification for clinical response to TOPOIIα inhibitors in breast cancer.35 For this reason, FISH testing for TOPOIIα status in addition to HER-2 evaluation may be useful in the characterization of Barrett’s pathology and progression to dysplasia. The gene discussed is ERBB2; the disease is breast cancer.