Background: The authors performed reexcision lumpectomy on patients with breast cancer with tumor at or close to the resection margin or if the margin status was unknown. Frozen section analysis (FSA) of reexcision lumpectomy margins was performed to allow additional excision of margins or mastectomy, saving the patient another operation or an additional radiation boost.
Methods: The authors reviewed the accuracy of FSA of margins in 107 patients undergoing reexcision lumpectomy between 1987 and 1992. There were 359 frozen sections performed on 156 specimens. Sensitivity and specificity of FSA for each frozen section margin, specimen, and patient were evaluated, as was gross inspection of tumor involvement at the resection margins. The accuracy of each pathologist's use of FSA also was evaluated.
Results: FSA sensitivity per frozen section margin, specimen, and patient was 0.90, 0.89, and 0.85, respectively. The specificity of gross inspection was 0.97, 0.96, and 0.96 (sensitivity, 0.44), which was significantly less accurate than that of FSA (P = 0.0015) or permanent section (P = 0.019). There was no significant discordance between FSA and permanent section. Of 19 pathologists doing FSA, 6 evaluated 10 or more specimens. The error rate ranged from 4% to 10% among pathologists with 10 or more readings, whereas 12 of 13 pathologists with fewer readings had no errors. The final pathologist had a 100% error rate, significantly worse (range, P = 0.0085-0.02) than any experienced pathologist. Thirty-four (32%) patients underwent additional excision (24 patients) or mastectomy (10 patients) based on the results of FSA, which saved the patients from undergoing another operation. No one required an additional operation or a mastectomy because of a false FSA result.
Conclusion: FSA is safe and accurate in evaluating reexcision lumpectomy margins. Gross inspection is not reliable in margin evaluation. FSA saved an additional operation 32% of the time. Obtaining clear margins during one procedure eliminates the necessity of an additional radiation boost and probably will improve cosmesis.