The prognostic role of Ki67 labelling index has been explored in these tumors and some studies demonstrated that the distinction of grade 1 and grade 2 does not correlate with prognosis [101, 102], while others showed that Ki67 > 3% (grade 2), tumor size > 15.5 mm, and presence of lymphatic and vascular infiltration are associated with higher propensity to lymph node metastases [103]. The gene discussed is MKI67; the disease is neoplasm.