Preoperative tumor size at MRI predicts deep myometrial invasion, lymph node metastases, and patient outcome in endometrial carcinomas.

Endometrial cancer is the most common gynecologic malignancy in industrialized countries, and the incidence is increasing.1 Surgical treatment is planned based on preoperative assessment of histological subtype, grade, and depth of myometrial invasion. Surgical International Federation of Gynecology and Obstetrics (FIGO) stage is documented to be the strongest prognostic factor in endometrial carcinoma, thus guiding adjuvant therapy in addition to the assessment of histologic subtype and grade in the hysterectomy specimen.1–3 Magnetic resonance imaging (MRI) has long been considered the diagnostic imaging method of choice for preoperative staging of endometrial carcinomas.4–6 The presence of deep myometrial invasion and cervical stroma invasion could be visualized, and enlarged lymph nodes could be detected. However, conventional pelvic MRI has reportedly limitations in accuracy in the detection of the staging parameters, in particular for detecting lymph node metastases.6,7 Interobserver variation between radiologists for all staging parameters also represents a source of inaccuracy.8 As opposed to the cervical cancer FIGO staging system,6 FIGO staging for endometrial cancers does not include tumor size measurements. Nevertheless, large macroscopic tumor size, assessed in the hysterectomy specimen, has long been known to predict lymph node metastasis and poor survival in patients with endometrial carcinomas.9–13 Recent publications support that tumor volume based on preoperative MRI predicts lymph node metastases and has prognostic impact in endometrial cancer.14,15 However, the reproducibility of MRI-based tumor measurements has, to our knowledge, not yet been explored. Furthermore, the optimal cutoff value for risk assessment based on tumor size is not yet defined. The primary objective of this study was to explore the relationship between different preoperative tumor size measurements using MRI and the surgical pathologic staging parameters deep myometrial invasion, cervical stroma invasion, and metastatic lymph nodes in endometrial carcinoma patients. The secondary objectives were to assess the interobserver variability for the different tumor measurements and to explore the value of these preoperative tumor size measurements to identify patients with poor outcome.