Racial and Ethnic Parities in Outcomes After Breast Conservation Therapy in Native Hawaiians

Abstract

Breast conservation therapy (BCT), combining breast conserving surgery and adjuvant radiation therapy, offers survival outcomes equivalent to those obtained with mastectomy for the treatment of breast cancer. While studies have documented racial/ethnic differences in breast cancer outcomes, little is known of the prognosis of Native Hawaiian (NH) patients. The objective of this study was to quantify the impact of NH ethnicity on outcomes following BCT, as compared to white and Japanese patients, who comprise the largest racial and ethnic groups within our dataset, respectively. In this retrospective cohort study, tumor registry data was reviewed for 1527 patients with Tis, T1, or T2 breast tumors treated with BCT between 1990 and 2004. Within the study dataset, patients were self-identified as 507 (33.2%) Japanese, 398 (26.1%) White, 327 (21.4%) other Asian, 242 (15.8%) NH, 22 (1.4%) other Pacific Islander, and 31 (2.0%) other ethnicities. The primary study outcome measure was overall survival (OS). Survival estimates were calculated using the Kaplan-Meier survival analysis and multivariable analysis (MVA) was adjusted for age and stage using Cox regression. Median follow-up was 8.9 years. Median age was 57 years old. On MVA, NH ethnicity had no significant impact on OS, as compared to white patients (HR 0.81, 95% CI: 0.54-1.22, P = 0.32, ref = NH), while Japanese race showed improved OS compared to NH (HR 0.33, 95% CI: 0.20-0.54, p<0.001, ref = NH) and white patients (HR 2.6, 95% CI: 1.6-4.1, P<0.001, ref = Japanese). NH patients treated with BCT share similar OS to that of white patients. Japanese patients experienced outcomes superior to those of both NH and white patients. More research is needed in order to understand these observed differences in survival.