Abstract C31: Exploring disparities in sentinel lymph node biopsy within the Breast Cancer Care in Chicago study
Authors: Irizarry Bethliz , Dookeran Keith , Rauscher Garth 
Published: May 2016

Background: Lymph node biopsy is a critical component of a diagnostic work-up for patients with invasive breast cancer and is necessary for evaluating the extent and stage of disease so that appropriate treatment can be recommended. The standard procedure prior to the advent of sentinel lymph node biopsy (SLNB) procedures was axillary lymph node dissection (ALND), which is associated with debilitating side effects such as lymphedema. SLNB diffused into practice during the early 2000s and is associated with fewer side effects; for this reason, SLNB has become the standard of care for women diagnosed with invasive breast cancer without clinically palpable lymph node involvement. Using data from the Breast Cancer Care in Chicago study (BCCC), we investigated racial/ethnic disparities in the receipt of SLNB vs. ALND and whether certain tumor, patient, or facility characteristics might help to explain the likelihood of receiving a SLNB.

Methods: A total of 989 female patients newly diagnosed with breast cancer were recruited and interviewed for the study. Eligible patients were female, resided in Chicago, had a first primary in situ or invasive breast cancer; were diagnosed between 2005 and 2008 between the ages of 30 and 79 at diagnosis; and self-identified as either non-Latina (nL) White, nL Black or Latina. Of these, 74% (N=731) consented to medical record abstraction and had complete information on receipt of either ALND or SLNB. The racial/ethnic disparity in receipt of SLNB was estimated as a prevalence difference (PD) using logistic regression with marginal based standardization. Mediation analyses were conducted using the method of rescaled coefficients (Karlson, Holm, and Breen). All models were adjusted for age at diagnosis.

Results: Roughly half of patients (57%) received a SLNB; nL White women were more likely to receive a SLNB as compared to nL Black and Hispanic women (67% vs 50% and 50%; p=&lt;.001). The prevalence of SNLB was 33%, 75%, 70%, 38% and 20% for stage 0, 1, 2, 3 and 4 breast cancer (p&lt;0.0001) and was higher for ER/PR positive versus negative tumors (p&lt;0.0001) and decreased with increasing tumor grade (p=0.007). SLNB did not vary appreciably for patients who were uninsured, publicly insured or privately insured and SLNB was more common for patients diagnosed at facilities with accreditations from the National Accreditation Program for Breast Centers (NAPBC) and the Commission on Cancer (COC) and less common for patients diagnosed at disproportionate share facilities (p&lt;0.05 for all). After adjusting for age, stage at diagnosis, and tumor characteristics, the disparity in receipt of SLNB was 24 percentage points. In mediation analysis, facility accreditation and disproportionate share status explained 43% of the disparity (p=0.030).

Conclusion: During the mid to late 2000s when the practice of SLNB as an alternative to ALND was reaching about half of eligible patients in Chicago, ethnic minority patients were less likely than their nL White counterparts to receive SLNB. Facility accreditation explained a substantial portion of this disparity. Better access and opportunities to go to highly accredited facilities may decrease this disparity.

Citation Format: Bethliz Irizarry, Keith Dookeran, Garth Rauscher. Exploring disparities in sentinel lymph node biopsy within the Breast Cancer Care in Chicago study. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C31.