Abstract: |
Background/Objective: Intraoperative evaluation of sentinel lymph nodes (SLNs) after neoadjuvant chemotherapy (NAC) has a higher false-negative rate than in the primary surgical setting, particularly for small tumor deposits. Additional tumor burden seen with isolated tumor cells (ITCs) and micrometastases following primary surgery is low; however, it is unknown whether the same is true after NAC. We examined the false-negative rate of intraoperative frozen section (FS) after NAC, and the association between SLN metastasis size and residual disease at axillary lymph node dissection (ALND). Methods: Patients undergoing SLN biopsy after NAC were identified. The association between SLN metastasis size and residual axillary disease was examined. Results: From July 2008 to July 2017, 702 patients (711 cancers) had SLN biopsy after NAC. On FS, 181 had metastases, 530 were negative; 33 negative cases were positive on final pathology (false-negative rate 6.2%). Among patients with a positive FS, 3 (2%) had ITCs and no further disease on ALND; 41 (23%) had micrometastases and 125 (69%) had macrometastases. Fifty-nine percent of patients with micrometastases and 63% with macrometastases had one or more additional positive nodes at ALND. Among those with a false-negative result, 10 (30%) had ITCs, 15 (46%) had micrometastases, and 8 (24%) had macrometastases; 17 had ALND and 59% had one or more additional positive lymph nodes. Overall, 1/6 (17%) patients with ITCs and 28/44 (64%) patients with micrometastases had additional nodal metastases at ALND. Conclusion: Low-volume SLN disease after NAC is not an indicator of a low risk of additional positive axillary nodes and remains an indication for ALND, even when not detected on intraoperative FS. © 2018, Society of Surgical Oncology. |