A Randomized Controlled Trial for Doing vs. Omitting Intraoperative Frozen Section Biopsy For Resection MArgin Status in Selected Patients Undergoing Breast Conserving Surgery

1.1 Preoperative work-up Preoperative breast MRI is recommended to assess multifocal/centric lesions and non-mass enhancement surrounding main mass. Preoperative needle localization or skin marking is done by each hospital's method.

1.2 Surgical procedure Initial wide excision is performed as usual. The recommended target gross margin is one finger breadth. Orientation of the specimen will be done according to each center's principle. Randomization for frozen section biopsy vs. omission is done intraoperatively, after initial wide excision. For the frozen section biopsy omission group, no further procedures will be done. For the frozen section biopsy group, frozen section biopsy is performed on the specimen or cavity by the operating surgeon. The precise method is decided by the surgeon's discretion, but the recommended method is as follows. A minimum 1 x 0.5cm size of breast parenchymal tissue will be excised at minimum four directions of the specimen or cavity with a thickness of approximately 0.1cm (Figure).

Additional resection according to frozen section biopsy result will be decided by the surgeon's discretion. After review of final pathology report, decision of second operation for re-excision will also be done by surgeon's discretion. A recommendation of considering re-excision for only a positive margin (tumor on inked margin) is noted but not mandatory. Data on additional resection or re-excision must all be reported.

1.3 Pathology procedure Evaluation procedure of the frozen section biopsy specimen and wide excision, additional excision specimen is done by each hospital's method. A pathology report of both intraoperative frozen section biopsy result and final pathology result of the frozen section biopsy tissue must be done. Gross specimen measurements (height x length x depth) must be specified on pathology report. Also margin status must be recorded, positive margin defined as "no ink on tumor" for DCIS and invasive cancer. Recording of margin distance from superior, inferior, medial, lateral, margin is recommended. If all margin distance is not feasible for recording, at least margin distance of closest margin must be recorded. The final pathology result of the additional resection specimen after frozen section result must describe whether residual cancer cells were present and the site of them. This is the same for re-operation resection specimens. Thorough microscopic examination for residual cancer cells in additional/re-operation resection specimens is warranted.

1.4 Postoperative care and adjuvant therapy Postoperative care will be performed as usual. Routine adjuvant care will be given, including adjuvant radiation therapy.