Who would have thought a single Ki67 measurement would predict long-term outcome?

Excerpt

Recent data from neoadjuvant studies, predominantly for endocrine therapy but also for chemotherapy, indicate that a single measurement of the nuclear proliferation marker Ki67 made in the breast carcinoma during/after neoadjuvant therapy is strongly predictive of long-term disease outcome. In an era when many mega-parameter signatures have been derived with the aim of improving the accuracy of prediction, it is superficially very surprising that a single immunohistochemical measurement can act in this fashion. This provokes a number of questions, and the following three are addressed below: What is the underlying reason for this predictive ability? Given that Ki67 is influenced by treatment/external factors and is not stable in the short term, why does it predict in the long term? What is the best time for measuring Ki67? …