Combined Frozen Section and Imprint Smear Assessment of Sentinel Node Improves Accuracy and Reduces False Negative Rates in Breast Cancer: A Prospective Study

Sentinel lymph node biopsy (SLNB) is standard of care for clinically negative operable breast cancer. However, the best technique for intra-operative assessment of SLN still remains a matter of research. Accuracy of frozen section (FS), which is widely used for detecting metastasis in SLN varies from 79 to 89% with false negative rate being 5.5 to 43%. This study was hence done to evaluate if combined intraoperative FS and imprint cytology (IC) evaluation improves accuracy and reduces false negative rate for SLN evaluation in breast cancer. In this prospective cohort study, patients with operable breast cancer with negative axillary lymph node status (N0) were included. SLNB was done using combination technique with a radionuclide tracer and blue dye. Smears were prepared from SLNs for imprint cytology evaluation and excised SLNs were then sent for frozen section. Diagnostic indices of frozen section, imprint cytology, and combined technique were assessed in terms of sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratios, false negative rate, and overall accuracy with 95% confidence intervals taking final histopathology as “gold standard.” Eighty-one cases of SLNB in which both FS and IC reports were available were included for analysis. Sensitivity (93.8%; CI 69.8–99.8%), specificity (100%; CI 89.3–100%), positive predictive value (100%; CI 66.3–100%), negative predictive value (98.4%; CI 91.6–100%), false negative rate (6.25%), and overall diagnostic accuracy (98.7%) of combined evaluation were superior as compared to either of the techniques. Combination of frozen section and imprint cytology has better diagnostic accuracy and reduced false negative rate as compared to either of them alone.