Frozen-section-guided breast-conserving surgery: implications of diagnosis by frozen section as a guide to determining the extent of resection.

This study was conducted to analyze retrospectively the results of performing sector resection on 56 breasts in 54 patients with breast cancer. The glands were resected with a 2-cm tumor-free margin on both lateral sides and the distal side, and with more than a 3-cm tumor-free margin on the nipple side. The frequency of positive resection margins for the cancer cells was 7/56 (12.5%) on the nipple side and 12/46 (26.1%) on the lateral sides, with an overall frequency of 15/56 (26.8%). There were positive resected margins for cancer cells on both the nipple and lateral sides in 4/46 patients (9%). Assuming the equivocal margins were positive for cancer cells, an accurate diagnosis by frozen section examination was made in 51 of the 56 operations (91.1%). Additional resection of the margins was performed in all 20 cases of a positive resected margin for cancer cells according to the diagnosis by frozen section. Thereafter, the resected margins became negative in 13 cases (65%), but remained positive in 7 cases (35%). These results show that performing diagnosis by frozen section of the surgical margins is an effective guide to resecting tumors adequately.