Utility of Intraoperative Frozen-Section Examinations of Surgical Margins: With Special Reference to the Implication of Features of Margin-Exposed Tumor Components on Further Surgical Treatment.

Abstract

Abstract Purpose: The assessment of surgical margins is important in breast conserving surgery (BCS). In BCS, we usually resect additional specimens after the diagnosis of positive margin by intraoperative frozen-section examinations (IFE). However, we often experience the patients who received additional resections after positive results by IFE but no tumors were detected in the permanent sections. If we can predict the absence of residual tumor components from IFE, it may be possible to avoid additional mastectomy. In the present study, we tried to identify histological characteristics of margin-exposed tumor components on IFE as predictive factors for the residual tumor components in the additionally resected specimens. Methods: 1,835 cases underwent BCS between October 1999 and July 2008 at the National Cancer Center Hospital, Tokyo, Japan. By the review of the pathological database, we chose patients who had positive surgical margins determined by IFE and had undergone immediate additional resection. Two observers (MK, HT) reviewed the slides of frozen sections and confirmed the presence of tumor components. Results: 220 cases (12%) were eligible for this study. Within the specimens of additional resection, residual tumors existed in 114 cases (51.8%) and no tumors existed in 106 cases (48.2%). As characteristics of the primary tumors, invasive lobular carcinoma, pT3, EIC(+) and lymphatic invasion were significantly associated with the residual tumor components. As characteristics of margin-exposed tumor components on IFE, the number of positive margins, their maximum diameter and histological type were correlated with the residual tumors. The rate of detection of the residual tumors was significantly higher in the group with multiple positive margins (50/72, 69%) than in the group with a single positive margin (64/148, 43%) (p=0.0003). The residual tumors were detected in 36.5% (38/104), 60.8% (62/102), and 100% (14/14) of the groups with <6 mm, ≥6 to <20 mm, and ≥20 mm of the maximum diameter of the exposed tumor components, respectively (p=0.0005). Although there was no significant relationship in the rate between the group with exposed noninvasive components and that with exposed invasive components, the residual tumor components were detected more frequently in the group with exposed lobular carcinoma components (20/29, 69%) than in the group with exposed ductal carcinoma components (94/191, 49%) (p=0.047). By a multivariate analysis, the number of positive margins and the maximum diameter were independent risk factors of the residual tumors. Conclusion: The diagnosis of positive margins by IFE was useful for the prediction of residual tumors, and three histological properties of margin-exposed tumor components were correlated with the absence of residual tumor components. It may be possible to consider stratification of additional surgical therapy according to the characteristics of margin-exposed tumor components on IFE. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4118.