REPEAT SENTINEL LYMPH NODE BIOPSY IN RECURRENT BREAST CANCER: PERITUMORAL VS. PERIREOLAR INJECTION
Most breast surgeons do not hesitate to perform a repeat sentinel node biopsy in patients with recurrent breast cancer. Similarly, most surgeons have migrated to periareoalar (PA) injection on initial surgery because of its simplicity and high sentinel node identification rates. However, PA injections have been shown to not reliably map breast lymphatics in non-axillary basins. To compare peritumoral (PT) and PA injection technique Guru et al. from the Mayo Clinic in Rochester, MN recently reported a retrospective review of a prospectively maintained database of patients aged >18 years who underwent repeat sentinel node biopsy (rSNB).
The study group included 141 patients with a recurrent or new ipsilateral tumor following lumpectomy and sentinel node biopsy in 94 patients or lumpectomy and axillary lymph node dissection (ALND) in 47 patients. The median time to recurrence was 9.8 years. Fourteen percent of patients underwent either neoadjuvant chemo or endocrine therapy. Mapping technique and agents were chosen by surgeon’s preference. Tc-99 sulfa colloid was used alone in 22%, whereas dual agent mapping was used in 78%. Blue dye alone was not used by any surgeon.
Lymphoscintigraphy was performed in 88.7% (125/141) of patients. Thirty had no nodes visualized. Successful retrieval of one or more sentinel nodes was accomplished in 73% (103/141) of patients. Sentinel node(s) were retrieved in 77% (76/99) in the PA radiotracer injection group, 63% (24/38) in the PT radiotracer group, and 75% (3/4) in patients injected in both locations. Sentinel node mapping success did not differ significantly between the 2 injection techniques (p=0.11). The success rate of rSNB in patients having prior SNB alone was 79.8% compared to 59.6% in those having prior ALND. Twenty-five patients were noted to have aberrant drainage on lymphoscintigraphy. No significant difference was noted in aberrant drainage when comparing the two injection techniques.
Intraoperative blue dye was used in 110 patients. Injection was PA in 92, PT in 13, both locations in 3 and other locations in 2. Among the 110 patients having radiotracer and blue dye injected, 179 sentinel nodes were removed. Of the 179 nodes, only 3 were identified by blue dye alone, all of which were negative for metastatic disease.
In patients having a successful rSNB, 12.6% (13/103) were positive for metastatic disease. Fifteen percent (11/76) were positive in the PA radiotracer group, 8% (2/24) in the PT group, and 0% (0/3) in patients injected in both locations. There were 3 positive sentinel nodes found in aberrant locations. One was found in the contralateral axilla detected by PA radiocolloid but not by blue dye. Two aberrant sentinel nodes were detected by PT radiocolloid injection, 1 in the contralateral axilla, and 1 internal mammary node.
On multivariable analysis, the variables which were predictive of failed mapping were BMI≥30, prior axillary node dissection, and prior tumor in the upper outer quadrant. Of the 38 patients having PT radiocolloid injection, 24 were injected intradermal, 13 intraparenchymal, and 1 both. Intradermal injection had the highest success rate at 75%, compared to 38% for intraparenchymal.
Conclusions: The authors found no statistical difference in the rSNB in either success rate, identification of aberrant drainage, or detection of positive nodes between PT or PA injection technique. The group at Mayo Clinic “have implemented a process of PA and intradermal PT injection of Tc-99 overlying the tumor with lymphoscintigraphy as our new standard for rSNB. Our findings are consistent with those of the Sentinel Node and Recurrent Breast Cancer (SNARBC) group, which demonstrated a low risk of regional recurrence in the setting of a negative rSNB and a low risk of regional recurrence if lymphatic mapping fails.”