Tangential Frozen Section Analysis for the Surgical Margins in Breast-conserving Surgery

Background: The optimal method used to assess surgical margins in breast-conserving surgery (BCS) has not been determined. Method: After wide excision was performed with macroscopic margins of at least 1 cm, surgical margins were evaluated on tangential sections by frozen section analyses (FSA). Positive margins prompted immediate surgical re-excision of the corresponding tissue. The results were compared with examination by permanent section (PS). Results: Using FSA, the initial margin was judged positive in 31 (18%) of 170 patients undergoing BCS. These patients underwent re-excision during surgery, but the margin of re-excised tissue was still positive in 10 patients on PS. Although the initial margin was negative on FSA in 139 (82%), on the other hand, the margins were shown to be positive on PS in 12 patients (false negative). The second operation was performed in 15 of these 22 patients. The rates of re-excision and second operation were 18% and 9%, respectively. The rate of breast tumor recurrence (BTR) was 0.5% at a median follow-up of 42 months. Conclusion: The tangential method allows a complete analysis of surgical margins, and a selective re-excision policy for margin positivity may result in low rates of second operation and BTR. Adoption of macroscopic margins of at least 1 cm is unlikely to increase the rates of BTR.