Prostate cancers in the transition zone: Part 2; clinical aspects

Unfortunately the definition of TZ cancers is not uniform, which may also explain the varying rate in different series. McNeal et al. [2] proposed a threshold of ≥ 70% of the cancer volume in the TZ to define the presence of a TZ tumour. However, later analyses from the same institution used a threshold of 50% of cancer volume, with the largest cancer focus called the ‘index tumour’ [4,6]. Notably, prostate cancers confined exclusively to the TZ, which can be termed ‘TZ cancer’, were only found in 2–7% of samples [5,7]. This variance in the definition of TZ should be considered when comparing different studies.