E63: Is Omission of Sentinel Node Biopsy (SLNB) for Low Risk Invasive Breast Cancers safe?

The ACOSOG Z11 trial clearly showed that leaving microscopic disease in the axilla does not result in a high rates of local recurrence. The Choosing Wisely guidelines recommend not routinely performing SLNB in women over the age of 70. As a result, omission of SLNB has become increasingly popular. We reviewed our experience with omitting SLNB to determine its safety.

Methods:

After IRB approval, a prospective breast cancer database was queried for patients not receiving SLNB as part of their surgical treatment. Patients with invasive breast carcinoma and at least 30 months of follow up were included. Those with prior ipsilateral axillary node dissection or prior ipsilateral mastectomy were excluded. Demographics, clinicopathologic features, treatment modalities, recurrence and survival outcomes data were extracted (Table 1).

Results:

A total of 64 patients with invasive cancer and no SLNB were evaluated. Most patients were over the age of 69 years (81.3%), caucasian (89.1%), and diagnosed on screening (76.6%). Most cancers were Stage 1, ER positive, and Luminal type A. In the younger age group (group A), only patients with smaller (cT0-cT1), clinical stage 0-1, ER positive, Luminal phenotype cancers did not have nodal staging. Reasons for omission of SLNB in this group included failure to map with low risk features (58.3%), low risk features and/or comorbidities (33%.3%), or patient choice (8.3%). In the older patient group (group B), reasons for omission of SLNB included Choosing Wisely (82.7%), failure to map with low risk features (5.8%) or patient choice (11.5%). Most patients in group A received hormonal adjuvant therapy and no patients received axillary nodal radiation. At a median follow up of 40.5 months only 1 patient had a nodal recurrence (1.6%). This was an 86 year old with significant comorbidities, presenting with a T2 triple negative breast cancer who declined chemotherapy. Her axillary recurrence was treated with radiation and she is without evidence of disease (NED) at 37 months post recurrence. In group A, all patients, but one who died of other causes, were alive and NED despite the omission of SLNB and axillary radiation. Most of the patients in group B were alive and NED at follow up (80.8%), one was alive with disease, receiving hormonal therapy for a local recurrence (1.9%), 7 died of other causes, and 2 patients died of disease after local and distant metastases.

Conclusions:

Overall, omission of SLNB in patients with low risk cancers appears to be safe, with low risk of regional recurrence. Considering the small size of this series, larger studies are needed to confirm these findings.