BMI1 and neoplasm: Among 21 pairs of samples for which the primary tumor and ovarian metastases were from the same patient, 6 pairs had inconsistent expression of Bmi-1, including 5 pairs with the ovarian metastasis showing positive Bmi-1 and the primary tumor showing negative Bmi-1, 1 pair with the ovarian metastasis showing negative Bmi-1 and the primary tumor showing positive Bmi-1, and the matching McNemar test demonstrated a trend of higher expression in the metastatic site than in the primary site (P = 0.063, Additional file 4: Table S1).