A prospective assessment of the reliability of frozen section to direct intraoperative decision making in endometrial cancer

Objective: To determine the reliability of intraoperative frozen sections (IFSs) for surgical staging of endometrial cancer (EC). Methods: Data were collected prospectively on 784 consecutive patients with EC who were undergoing a hysterectomy at our institution from January 1, 2004, to December 31, 2008. The need for surgical staging was decided through IFS using 4 variables: tumor size, histologic grade, histologic subtype, and depth of myometrial invasion (MI). The IFS results were compared with the permanent paraffin sections (PSs) to assess for discordances. Results: In 30 of the 784 cases (4%), the PS pathology report was amended with discordant results. In addition, a definitive diagnosis of the 4 parameters was deferred to PS in 53 cases (7%), of which 30 (4%) were concordant and 23 (3%) were discordant. IFS-related deviations from the prescribed surgical algorithm occurred in 10 cases (1.3%; 95% confidence interval, 0.6%-2.3%). Of these 10 cases, 3 were amendments after PS review and 7 were IFS deferrals for definitive PS interpretation. Conclusions: Clinically significant discordance between IFS and PS occurred in only 1.3% of cases. Despite skepticism expressed in the medical literature, IFS provides highly reliable data to guide intraoperative treatment decisions at institutions with sufficient pathologic expertise.