Proliferation Index Determined by MIB-1 and Recurrence in Endometrial Cancer

Background: Endometrial carcinoma is the most common gynecologic malignancy in developed countries. Stage, grade, DNA index, histologic type, depth of invasion, steroid receptor status, and the presence of positive peritoneal cytology have all been linked to survival. The monoclonal antibody MIB-1 reacts with the same antigen as Ki-67 giving an estimate of proliferation index. The authors investigated whether MIB-1 staining, using image analysis, could be used as a prognostic indicator of recurrence in endometrial carcinoma. Methods: The tumors from 39 consecutive patients receiving primary surgical therapy for endometrial cancer were evaluated with the MIB-1 monoclonal antibody. Proliferation index was quantified by image analysis. The patients were followed for a median of 34 months and their charts were reviewed to determine recurrence, histologic type, grade, stage, depth of invasion, and status of peritoneal cytology. Results: Eleven of the 39 patients had recurrence of their disease within the 3-year observation period of this study. Overall, 22 patients had stage I disease, 3 patients had stage II disease, 12 patients had stage III disease, and 2 patients had stage IV disease. MIB-1 staining was not significantly elevated in advanced (stage III and IV) as opposed to early (stage I and II) cancers (P= 0.558). Elevated MIB-1 staining was associated with an increased incidence of recurrence within 24 months of diagnosis (P= 0.002). Patients whose tumors had MIB-1 staining of greater than or equal to 39.0% had an increased chance of recurring over patients whose tumors stained less than 39.0% (P= 0.003). Conclusion: In this series of 39 patients with endometrial cancers, MIB-1 monoclonal antibody staining was shown to be a prognostic indicator of recurrence.