Predictive value of herceptest IHC and pathvysion FISH data: Analysis from a trastuzumab phase II monotherapy study.

Abstract Conclusion: Under standardized conditions IHC and FISH show high concordance. However these results indicate that when testing with FISH it may be worth checking for polysomy.

Note: 3 patients (out of a study of 300 patients) were found to respond to herceptin despite being "FISH - negative." In that case testing for C17 polysomy was suggested.