[Comparison of two HER-2 FISH kits on formalin-fixed paraffin-embedded tissues: signal detection and simple procedure].

The gene amplification of human epidermal growth factor receptor (HER-2) detected by fluorescence in situ hybridization (FISH) help to select breast cancer patients who could benefit from therapeutic strategies targeting HER-2, trastuzumab. For formalin-fixed paraffin-embedded tissue specimens, the preprocessing procedure, which is consisted of heat-treatment and protease digestion, is necessary to detect probe specific signal by FISH. We compared the findings of two commercial kits for HER-2 (Histra HER2 FISH Kit [JOKOH CO.LTD] and Pathvysion HER-2 DNA Probe Kit [Abbot Molecular CO. LTD]) using 9 breast cancer specimens, which were fixed in formalin for various durations after the surgical extirpation or biopsy. The two kits showed the same results that HER-2/17 centromere (17cen) signal ratio was within normal rage (< 2.0) in 7 cases among 9 and was over 2.0 in remaining 2. Histra could obtain sufficient signals on both surgical and needle biopsy speciments after the same pretreatments. PathVysion, on the other hand, require a different protease or modification of protease digestion time. Furthermore, the specific signals for HER-2 and 17cen could be observed more clearly by Histra than PathVysion under fluorescensce microscope. Histra is more suitable for routine examination because of its simple and constant-processing procedure.