Repeat Sentinel Lymph Node Surgery in Recurrent Breast Cancer: Peritumoral vs. Periareolar Injections

•Approximately ¼ of patients undergoing repeat SLNB have aberrant drainage and approximately ¼ have failed mapping•Lymphoscintigraphy should be strongly considered when performing repeat SLNB•History of prior radiation to the breast or axilla, prior ALND, resection of >5 nodes at prior axillary surgery, prior tumor in upper outer quadrant and BMI ≥ 30 were associated with failed mapping at the time of rSLN surgery.•Factors associated with aberrant lymphatic drainage include a history of prior ALND, >5 nodes removed at prior axillary surgery and a time interval of >5 years between the primary tumor treatment and diagnosis of recurrence. In the setting of recurrent cancer, there is no standard methodology regarding the technical aspects of repeat sentinel lymph node (rSLN) surgery. We analyzed our institutional experience with attempted rSLN surgery to determine the optimal injection technique. Single site, retrospective review of patients with prior lumpectomy for breast cancer who presented with recurrent or new ipsilateral breast cancer and underwent attempt at rSLN surgery from 2008 to 2017. Patients with prior mastectomy or no prior ipsilateral axillary operation were excluded. A total of 141 patients were included; 103 (73%) underwent successful rSLN biopsy procedure. Lymphoscintigraphy showed aberrant drainage in 32 (26%). Periareolar (PA) injection resulted in failed mapping in 23/99 (23%) and aberrant drainage in 25/85 (29%). By comparison, peritumoral (PT) injection had a 14/38 (37%) incidence of failed mapping and 7/37 (19%) aberrant drainage (P = .11 and .23, respectively). Of the patients with successful sentinel lymph node (SLN) biopsy procedure via PA injection, 11/76 (14%) were positive for metastatic disease as compared with 2/24 (8%) in PT injection. Sixteen patients had lymph node metastases; 13 (81%) were SLNs, including 3 positive aberrant SLNs. Five-year regional recurrence rates were 11.4% (95% confidence interval, 0%-21.5%) and 0% for PA and PT injection techniques, respectively. PA and PT injections had a similar incidence of SLN identification and aberrant drainage. Preoperative lymphoscintigraphy is beneficial in patients with recurrent breast cancer given the higher incidence of aberrant drainage in this population. Patients who underwent PA injections had a higher incidence of regional recurrences but this difference was not statistically significant. There are limited data on the optimal injection technique for repeat sentinel l