Accuracy of frozen-section diagnosis at surgery in clinical stage I and II endometrial carcinoma.

OBJECTIVES: The purpose of our study was to determine if frozen section accurately identifies certain poor prognostic pathologic factors in endometrial carcinoma that are known to be associated with pelvic and paraaortic nodal metastasis, including deep myometrial invasion, poorly differentiated tumor, cervical invasion, adnexal involvement, and poor histologic type. STUDY DESIGN: The frozen-section pathologic results of 199 patients with clinical stage I and II endometrial cancer were retrospectively compared with permanent-section pathologic findings. RESULTS: The depth of myometrial invasion (superficial third vs deep two thirds) was accurately determined by frozen-section diagnosis at surgery in 181 of 199 cases (91.0%). The sensitivity of frozen-section diagnosis for deep myometrial invasion was 82.7%, and the specificity was 89.1%. The following tumor characteristics were accurately determined on frozen section at surgery: poorly differentiated tumor (95.0%), cervical invasion (94.0%), adnexal involvement (98.5%), and histologic type (94.0%). Frozen section underestimated deep myometrial invasion in 17.3% of patients with this characteristic and poorly differentiated tumor in 26.3% when compared with permanent-section diagnosis. In patients with unfavorable histologic types, papillary serous and adenosquamous carcinomas were the most commonly misdiagnosed histologic types by frozen section at surgery (70.6%). However, when the preoperative curettage pathologic findings were included, these inaccuracies in tumor grade and histologic type dropped to 15.8% and 35.3%, respectively. Only 13 of 199 patients (6.5%) were not correctly identified by frozen section at surgery as having poor prognostic pathologic features. CONCLUSION: Frozen section diagnosis at surgery is an important procedure that enables the surgeon to identify patients at high risk for pelvic and paraaortic nodal metastasis.