Frequency of sentinel lymph node (SLN) metastases in triple negative breast cancer (TNBC) versus non-TNBC
Ivanics T, Petersen L, Nathanson D, Davis M, Susick L, Lehrberg A, Rakitin I, Bensenhaver J, Proctor E, and Newman L. Frequency of sentinel lymph node (SLN) metastases in triple negative breast cancer (TNBC) versus non-TNBC. Ann Surg Oncol 2018; 25(Suppl 1):S92.
Ann Surg Oncol
INTRODUCTION: Primary tumor size has historically had a direct correlation with risk of nodal metastatic disease, and adjuvant chemotherapy is recommended for the majority of node-positive breast cancers. The published literature to date however, has revealed inconsistent data regarding associations between nodal status and size of TNBC tumors. Studies revealing high rates of nodal metastases among cases of small TNBC therefore raise questions regarding the value of breast cancer screening to detect subclinical TNBC among populations at increased risk for this phenotype, such as African Americans (AAs). Our goal was to evaluate nodal status correlated with primary tumor size in a diverse population treated in metropolitan multi-hospital health care system. Methods: We utilized an IRB-approved, prospectively-maintained database of patients (pts) undergoing SLN biopsy for clinically node-negative breast cancer. Results: A total of 2,438 SLN pts 1998 to 2017 were evaluated (median age 61, range 24-94 years); 897 AA (36.8%; median age 60 years) and 1,541 WA (63.2%; median age 63 years). Frequency of TNBC was 17.3% (155/897) among the AAs compared to 11.4% (175/1541) among White Americans (WAs) (P<0.01). Overall frequency of metastatic SLNs was similar for TNBC compared to non-TNBC pts (19.9% versus 21.0%) and for AAs compared to WAs (19.7% versus 21.5%). Mean tumor size (cm) was larger for the SLN-positive compared to SLN-negative cases (2.28 versus 1.58; p<0.01). Mean primary tumor size was also larger for the TNBC compared to non-TNBC cases (2.1 versus 1.8; p<0.05). Correlations between larger primary tumor size and increased frequency of SLN mets persisted after stratifying for race and for TNBC versus non-TNBC phenotype (see figure). Conclusion: In contrast to studies demonstrating that risk of nodal metastases is similar regardless of tumor size in TNBC, we found a direct correlation between tumor size and nodal status which was similar for AA and WA women. Early detection of TNBC can therefore reduce the likelihood of pts needing adjuvant chemotherapy and may reduce breast cancer outcome disparities between AA and WA pts.