Importance and use of a particular tumor marker may change depending upon the clinical scenario, ranging from initial presentation to differential diagnosis to recurrence.[2] Thus, for example, while tissue tumor markers like Cytokeratin, smooth muscle antigen (SMA), etc., may be extremely useful in categorization of malignancy, they are of no use in prognosis or monitoring; on the other hand, markers like Ki-67 (proliferation index) may help in prognostication or choice of therapy but have no role in the diagnostic arena. The gene discussed is MKI67; the disease is neoplasm.