Abstract S2-3: Disparities in the utilization of axillary sentinel lymph node biopsy among black and white patients with node-negative breast cancer from 2002–2007.
Authors: Black DM , Jiang J , Kuerer HM , Buchholz TA , Smith BD 
Published: August 2014

Background: Disparities exist in many aspects of standard breast cancer treatment in certain patient populations. In the mid-1990s, axillary sentinel lymph node biopsy (SLNB) was introduced as an alternative to axillary lymph node dissection (ALND) for staging clinically node-negative breast cancer. During the early 2000s, the validity of SLNB was being determined and its technique was being disseminated throughout the surgical community. By the mid to late-2000s, SLNB had been shown to provide accurate axillary staging with lower complications and no difference in survival compared to ALND in node-negative patients. SLNB has now replaced ALND as the accepted method for staging early breast cancer. The purpose of this study is to examine differences in the utilization of SLNB in pathologic node-negative invasive black breast cancer patients compared to white patients as SLNB became standard axillary staging and whether this difference impacted patient complications.

Methods: Using the population-based Surveillance, Epidemiology, and End Results (SEER)-Medicare data, cases of incident, non-metastatic, pathologic node-negative breast cancer in women age≥66 were identified. Patients were considered to have undergone SLNB if specified by SEER records or if a billing claim for axillary lymphatic mapping was identified. Unadjusted associations of SLNB with race were evaluated using the chi-square test. The Cochran-Armitage test evaluated trends over time. Multivariate logistic regression tested whether race was associated with the use of SLNB after adjustment for clinicopathologic factors. Five-year cumulative incidence of lymphedema assessed via ICD-9 diagnosis codes was measured using the Kaplan-Meier method. Adjusted proportional hazards regression evaluated assiciations of race and ALND with lymphedema risk.

Results: Of 31,274 women identified, 1,767 (5.7%) were Black, 27,856 (89%) were White and 1,651 (5.3%) were of other/unknown race. SLNB was performed in 74% of white patients compared to 62% of black patients (P&lt;0.001). Although use of SLNB increased by year for both black and white patients (P&lt;0.001), a fixed disparity in the use of SLNB persisted through 2007.

In adjusted analysis, black patients were 33% less likely than white patients to undergo SLNB (relative risk = 0.74, 95% CI 0.67-0.81; P&lt;0.001). Five-year cumulative incidence of lymphedema was 11.4% in patients undergoing ALND vs. 6.3% in patients undergoing SLNB (adjusted HR 1.92, 95% CI 1.75-2.10; P&lt;0.001). Overall, black race was also associated with a higher risk of lymphedema (adjusted HR 1.40; 95% CI 1.20-1.63; P&lt;0.001). However, among patients undergoing SLNB, whites and blacks had similar risks of lymphedema (6.2% and 7.7%, respectively; P=0.08).

Conclusion: Even with the increased use of SLNB and its acceptance as standard axillary staging for node-negative breast cancer patients, disparities persist in its underutilization in appropriate black patients compared to white patients by as much as 26%. This racial disparity in SLNB use translated to a higher risk of lymphedema for black patients. Improving surgeon practices, the multidisciplinary team approach, and patient education are important in optimizing the beneficial impact of SLNB and reducing complications from unnecessary ALNDs in all patients with early stage breast cancer. Future research is needed to delineate mechanisms underlying this persistent disparity and to identify strategies to mitigate it.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S2-3.