BackgroundThe usefulness of re-sentinel node biopsy (re-SNB) is unclear in the management of patients with ipsilateral recurrent breast cancer. MethodsWe retrospectively reviewed 52 patients with locally recurrent breast cancer who underwent re-SNB from July 2012 to March 2019. Both radioactive colloid and indocyanine green were used in all cases. ResultsForty-four patients were after SNB and 8 were after axillary lymph node dissection(ALND). SLNs were successfully visualized by lymphoscintigraphy in 94.2% (49/52) of cases (95.4% post-SNB vs. 87.5% post-ALND, Fisher’s exact test, p=0.401). Among post-SNB patients with successful mapping, 50% had SLNs only in ipsilateral axilla(I) and 50% had at least one SLN in other regions(contralateral axilla [C] and/or parasternal region [P])with or without SLN in (I), compared to 28.6% and 71.4% in post-ALND cases respectively(p=0.424). Among post-SNB cases with prior breast irradiation (n=37), 44.4% had SLN only in (I) and 55.6% had at least one SLN in other regions, compared to 83.3% and 16.7% in cases without prior irradiation (n=7) (p=0.184), respectively. While these differences were not significant, a lower rate of visualization and higher frequency of aberrant lymphatic flow in post-ALND than those in post-SNB was noted, and prior irradiation might affect lymphatic flow. We tried re-SNB for 47 cases and SLNs were successfully removed in 45 (95.7%) patients (92.8% in post-SNB, 100% in post-ALND). Re-SNB for (I) was performed for all cases with hot spots in (I) and one case without hot spot. Re-SNB for (C) or (P) were decided based on physician’s judgment. The SLN identification rates by site were 92.1% (35/38) for (I), 90.0% (9/10) for (C), and 100% (3/3) for (P). Sentinel node metastasis was found in three cases, all of which were in (I). ALND was performed in one case with macrometastasis but was omitted in two cases with micrometastases. The median follow-up duration after re-SNB was 22 months and no recurrence was observed. ConclusionsSentinel node identification was possible with high detection rates among patients with recurrent breast cancer after prior breast-conserving and axillary surgery. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureT. Yamanaka: Honoraria (self): Chugai; Honoraria (self): Eisai; Honoraria (self): Novartis Pharma; Honoraria (self): Taiho; Honoraria (self): Phizer Japan. T. Yamashita: Honoraria (self), Research grant / Funding (institution): Chugai; Honoraria (self): Eisai; Honoraria (self): Novartis Pharma; Honoraria (self): Taiho; Honoraria (self), Research grant / Funding (institution): Nippon Kayaku; Honoraria (self): AstraZeneca; Honoraria (self), Research grant / Funding (institution): Kyowa kirin; Honoraria (self): Phizer Japan; Honoraria (self): Takeda. N. Suganuma: Honoraria (self): Eisai; Honoraria (self): Novartis Pharma; Honoraria (self): Taiho; Honoraria (self): Kyowa kirin; Honoraria (self): Phizer Japan. All other authors have declared no conflicts of interest.