Sentinel node biopsy and regional recurrence following neoadjuvant chemotherapy in patients with isolated tumor cells: A rare event.

Abstract

e12581 Background: Lack of consensus exists regarding the optimal surgical axillary management of breast cancer patients treated with neoadjuvant therapy followed by sentinel node biopsy (SNB) with only isolated tumor cells (ITCs) identified in the sentinel node (SN). Few studies with limited patients have addressed this. A prospectively maintained database was reviewed to identify residual nodal metastatic burden and outcomes for patients with SN ITCs. Methods: Operable breast cancer patients treated with neoadjuvant therapy followed by breast surgery with SNB were identified who had only ITCs in the SN. Patients were excluded who had recurrent breast cancer, metastatic disease at time of operation, or who had an operation performed at another institution. Residual burden of axillary metastatic disease in patients who underwent completion axillary dissection and locoregional recurrence were examined. All SNs were examined with both hematoxylin and eosin stains as well as well as immunohistochemical stains. Results: 875 patients underwent neoadjuvant therapy followed by breast surgery and SNB from July 2007 to November 2021. Seventeen patients (1.9%) had only ITCs in the SN. The mean patient age of these 17 patients was 55.6 years (range 31-83 years). The majority had invasive ductal carcinoma (n = 15, 88.2%). Fourteen patients (82.4%) had ER+ tumors, 11 (64.7%) PR+ tumors, 2 patients (11.7%) had HER2+, and 3 patients (17.6%) had triple negative cancers. All patients had clinical T1 to T3 tumors and clinical N0 (n = 11, 64.7%), N1 (n = 5, 29.4%), or N2 (n = 1, 5.9%) disease. Two patients had isolated tumor cells identified on frozen section. Both of these patients underwent axillary dissection during the index operation and had further nodal disease identified (1 patient with ITCs only and 1 patient with macrometastasis). Fourteen patients had SN tumor free frozen sections but ultimately had ITCs identified with H&E. Five of these patients underwent a completion axillary dissection. Three of the 5 patients (60%) had additional ITCs identified after completion ALND. Fourteen patients had nodal irradiation. The three patients who did not receive irradiation did not undergo ALND. All patients with ER+ tumors received adjuvant endocrine therapy, the 2 patients with HER2+ cancers received adjuvant targeted HER2 therapy, and 4 patients received adjuvant chemotherapy. At a mean follow-up of 21.8 months (range 2-63 months), no locoregional recurrences occurred in any patient. Conclusions: ITCs in the SN after neoadjuvant therapy is a rare finding and are unlikely to be associated with regional recurrence.