Racial and Ethnic Differences in Breast Inflammation and Its Association with Lymphedema Risk After Axillary Lymph Node Dissection.

Abstract

Chronic inflammatory responses initiated by lymphatic injury play a key role in the pathophysiology of secondary lymphedema; however, it is unknown if these responses vary by race/ethnicity. We assessed whether baseline differences in inflammation, characterized by crown-like structures of the breast (CLS-B), contributed to lymphedema risk in a diverse cohort of patients treated with axillary lymph node dissection (ALND). Between 11/2016-03/2020, patients undergoing ALND were enrolled in a prospective lymphedema screening study. Race/ethnicity were self-reported. BMI and volumetric arm measurements were performed at baseline and biannually. Breast tissue was assessed for CLS-B utilizing a CD-68 IHC stain in non-tumor tissue. Lymphedema incidence was assessed using competing-risk analysis and compared between patients with and without CLS-B. Of 281 patients included, 11% self-identified as Asian, 20% Black, 8% Hispanic, 58% White, and 3% unknown. Median BMI was 26.3kg/m²; median follow-up was 2.99 years. Overall, 54% had CLS-B; prevalence varied by BMI (36% [BMI < 25], 63% [BMI 25-30], 70% [BMI > 30], p < 0.001) and by race/ethnicity (68% Black/64% Hispanic vs. 59% Asian/46% White, p = 0.02). The 2-year lymphedema rate was higher among Black and Hispanic women (32% Black/27% Hispanic versus 15% Asian/17% White, p = .012), and among women with CLS-B (27% vs. 12% [no CLS-B], p = 0.03). On multivariable analysis, Black race (p = 0.009), neoadjuvant chemotherapy receipt (p = 0.024), and older age (p = 0.002) were independently associated with lymphedema development, while CLS-B was not (p = 0.3). The higher CLS-B prevalence observed in Black women suggests an increased propensity for inflammation, although its role in lymphedema development remains uncertain.