Mildly interesting -- this small retrospective look found that FISH ratio correlated with ER negativity (higher ratios as ER decreased, or perhaps vice-versa): "Methods: Of the 80 HER2-positive (IHC3+/FISH+) BC, quantitative HER2 FISH ratio (widely spread over 1-18.3) and ER correlation was noted (r=0.34, p=0.002). Moreover, HER2 ratio (>4) correlated with higher Ki-67 (r= 0.5, p=0.01) and grade (p trend=0.05) in ER-positive subtype, inferring a biologic cut-point." Full abstract here:
http://www.asco.org/ascov2/Meetings/...stractID=35388 . "
If you search the archives, there will be discussions of ratio numbers. I think there have been a few small studies that thought they'd found significance (to prognosis, if I remember correctly) of ascending HER2 FISH levels, but most studies have not been able to find any correlations. It seems that most of the current questions in this arena center around that in-between area (some name it as being 1.8-2.2, other just say IHC+ but FISH negative). If anyone has looked recently at significance of high vs. low ratio numbers, I don't find it in a quick googling.
Debbie Laxague