Despite Ki-67 being considered a practical biomarker of cancer proliferation, it was not included in the signature [131]; however, it has been proposed that Ki-67 may be a comparable biomarker to the 70-gene signature in guiding adjuvant therapeutic decision making (p < 0.001), which is unsurprising as increased Ki-67 is useful in predicting disease recurrence [70,132,133]. The gene discussed is MKI67; the disease is cancer.