Racial disparities in disease‐specific mortality and surgical management of patients with ductal carcinoma in situ with microinvasion

Abstract Background and Objectives Given persistent racial disparities in breast cancer outcomes, this study explores racial differences in disease‐specific mortality and surgical management among patients with microinvasive ductal carcinoma in situ (DCIS‐MI). Methods The Surveillance, Epidemiology, and End Results Program was queried for patients aged 18+ years with DCIS‐MI between January 1, 2010 and December 31, 2018. The study cohort was divided into non‐Hispanic Black (NHB) and non‐Hispanic White (NHW) patients. Disease‐specific mortality was evaluated using Cox proportional hazards models. Results A total of 3400 patients were identified, of which 569 (16.7%) were NHB and 2831 (83.3%) were NHW. Compared with NHW patients, NHB patients had more positive lymph nodes (7.6% vs. 3.9% p < 0.001). In addition, NHB women were more likely to undergo axillary lymph node dissection (6.0% vs. 3.8%, p = 0.044) and receive chemotherapy (11.8% vs. 7.2%, p < 0.001). There were no racial differences in breast surgery type ( p = 0.168), reconstructive surgery ( p = 0.362), or radiation therapy ( p = 0.342). Overall, NHB patients had worse disease‐specific mortality (adjusted hazard ratio 2.13, 95% confidence interval CI: 1.10–4.14) with mortality risks diverging from NHW women after 3 years (6 years rate ratio RR 2.12, 95% CI: 1.13–4.34; 9 years RR 2.32, 95% CI: 1.24–4.35). Conclusions NHB women with DCIS‐MI present with higher nodal disease burden and experience worse disease‐specific mortality than NHW women.