Sentinel lymph node biopsy in contralateral prophylactic mastectomy: are we overtreating? Experience at a tertiary care hospital.

Objective: Use of routine sentinel lymph node biopsy (SLNB) in contralateral prophylactic mastectomy (CPM) is controversial. This retrospective study was undertaken to determine the frequency of SLNB in CPM at a community hospital and its utility as a guide to patient decision making.

Methods: Between 2007 and 2009, 170 patients underwent CPM at a suburban, tertiary care facility. The CPM was either immediate or delayed, or was for ipsilateral recurrent breast cancer. Thirty-seven (21.8%) of 170 patients had SLNB performed with CPM. The mastectomy specimens underwent standard pathologic evaluation by using intraoperative touch preparation cytology and postoperative hematoxylin and eosin staining and immunohistochemistry.

Results: No patients who underwent SLNB had positive nodes on touch preparation or final hematoxylin and eosin staining (0/37 [0%]). Fourteen (8.2%) of 37 patients had additional nodes identified in the specimens. These were either axillary tail or intramammary nodes. The median number of SLNs removed was 2 (range, 1-5), none of these were positive. There were 3 incidental cancers diagnosed on final pathology. Two invasive cancers (T1a and grade I) and 1 ductal carcinoma in situ were identified. SLNB was only performed on the patient with DCIS. Neither SLNB nor subsequent axillary lymph node dissection was performed in the invasive cancers.

Conclusions: SLNB was performed in 37 (21.8%) of patients who underwent CPM in a community hospital. Only 3 (1.76%) of 170 patients who underwent CPM had findings on final pathology that would have justified axillary staging. This correlates with other published data regarding SLNB in CPM. Because SLNB is associated with significant morbidity, guidelines for SLNB in prophylactic mastectomy need to be established so to avoid overtreatment.