SSO 2018: Is Low-Volume Disease in the Sentinel Node After Neoadjuvant Chemotherapy an Indication for Axillary Dissection?
Frozen section evaluation of sentinel lymph nodes after neoadjuvant chemotherapy has a higher false-negative rate than in the primary surgical setting, particularly for small tumor deposits. However, it is unknown whether similar false positive rates occur after chemotherapy.
Researchers led by Tracy-Ann Moo, MD, of Memorial Sloan Kettering Cancer Center, examined the false-negative rate of frozen sections after chemotherapy and the association between the size of sentinel lymph node metastasis and residual axillary disease at axillary dissection. Their findings were presented at the 2018 Society for Surgical Oncology (SSO) Annual Cancer Symposium (Abstract 47).
Findings
Dr. Moo and her team examined 702 patients undergoing sentinel lymph node biopsy after chemotherapy from a prospectively maintained institutional database. On frozen section, 181 had metastases and 530 were negative; 33 negative cases were positive on final pathology for a false negative rate of 6.2%.
Among patients with a positive result on frozen section, only 2% had isolated tumor cells and no further disease on dissection, while 41 (2%) had micrometastases and 125 (69%) had macrometastases. Of those, 59% with micrometastases and 63% with macrometastases had at least one or more than one additional positive lymph node at dissection. Patients with macrometastases had greater numbers of additional positive nodes.
Low-volume disease in the sentinel lymph node after chemotherapy is not an indicator of a low risk of additional positive axillary nodes. These tumor cells are potentially drug-resistant and are an indication for axillary dissection, even when not detected on intraoperative frozen section.
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