Predictors of final histology in patients with endometrial cancer.

Objective: To assess the usefulness of preoperative tumor grade and intraoperative assessment of gross depth of myometrial invasion as "predictors" of final grade, final depth of myometrial invasion and surgical stage in patients with "low-risk" endometrial cancer.

Methods: We retrospectively compared preoperative histology and intraoperative gross depth of invasion with final pathologic evaluation on hysterectomy specimens. For patients traditionally considered intraoperatively to be "low-risk" for lymph node metastasis (grade 1 or 2 adenocarcinoma with less than 50% myometrial invasion), "predictors" combining preoperative histology and intraoperative gross depth of myometrial invasion were established; that is, a preoperative biopsy of grade 1 adenocarcinoma with an intraoperative gross depth of myometrial invasion of 30% was assigned the predictor IbG1 (Stage Ib, grade 1). These predictors were then compared to final grade and surgical stage. Sensitivity, specificity, and positive predictive value were then calculated.

Results: A total of 153 patients had both a preoperative biopsy and intraoperative assessment of gross depth of invasion. Twenty-four patients had the IaG1 predictor; eight had stage IaG1 on final pathologic evaluation (sensitivity, 0.50; specificity, 0.88; positive predictive value, 0.33). Eight patients had the IaG2 predictor; none had stage IaG2 on final pathologic evaluation (sensitivity, 0; specificity, 0.95; positive predictive value, 0). Eighty-nine patients had the IbG1 predictor; forty-six had stage IbG1 on final pathologic evaluation (sensitivity, 0.72; specificity, 0.52; positive predictive value, 0.52). Thirty-two patients had the IbG2 predictor; 11 had stage IbG2 on final pathologic evaluation (sensitivity, 0.46; specificity, 0.84; positive predictive value, 0.34).

Conclusion: A clinically significant number of patients will have more advanced disease than predicted by preoperative or intraoperative prognostic factors. These predictors should not be relied on in the staging of endometrial cancer.