Preoperative Pelvic MRI and Serum Cancer Antigen-125: Selecting Women With Grade 1 Endometrial Cancer for Lymphadenectomy

OBJECTIVE. The objective of our study was to determine the predictive value of preoperative pelvic MRI and serum cancer antigen-125 (CA-125) evaluation in selecting women with grade 1 endometrial cancer for lymphadenectomy as part of the cancer staging operation. MATERIALS AND METHODS. A new preoperative clinical protocol including MRI and CA-125 evaluation was adopted at our institution in patients with grade 1 endometrioid adenocarcinoma. Lymphadenectomy was considered as part of the surgical staging operation if there was an elevated CA-125 value or a positive MRI finding (>= 50% myometrial invasion, cervical invasion, abnormal lymph nodes, extrauterine disease, or tumor index >= 36 cm). From January 2012 through May 2013, a retrospective analysis was performed of 100 women who underwent preoperative MRI and CA-125 evaluation; we refer to this cohort as the preoperative study cohort. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using final surgical pathology and CA-125 results as the reference standard. The rate of metastatic lymph nodes in the preoperative study cohort was determined. From May 2009 through January 2011, a retrospective analysis of a cohort who did not undergo preoperative MRI and CA-125 evaluation was undertaken to compare lymphadenectomy and lymph node metastasis rates before and after implementation of the new protocol; we refer to this cohort as the historical cohort. RESULTS. The new clinical protocol had sensitivity of 94%, specificity of 91%, PPV of 84%, and NPV of 97%. When histologic grade alone was considered, positive lymph node rates in the preoperative study cohort was 4.0% versus 4.2% in the historical cohort. In the preoperative study cohort, the lymph node metastasis rate increased to 11.1% with a positive MRI finding or elevated CA-125 value. CONCLUSION. Preoperative MRI and CA-125 evaluation identified women for lymphadenectomy with a high NPV.