In line with this, when considering HIF-1α IHC on three levels (negative, low and high), the IBTRs most often had the same HIF-1α staining intensity as their corresponding primary tumour (65%, n = 75), while 21% (n = 24) of the IBTRs had increased intensity, and 14% (n = 16) had decreased HIF-1α intensity. Here, HIF1A is linked to neoplasm.