However, the novel results obtained in the present study may be limited by the PgR cut-off values selected, and, thus, further prospective and large-scale clinical research appears to be necessary in order to confirm the most suitable cut-off value for PgR expression as a prognostic factor for the Ki67-intermediate group in ER-positive/HER2-negative breast cancer patients. The gene discussed is MKI67; the disease is breast carcinoma.