P1-11-02: Racial/Ethnic Differences in Adjuvant Trastuzumab Receipt for Women with Breast Cancer within the National Comprehensive Cancer Network.
Authors: Freedman RA , Hughes ME , Ottesen RA , He Y , Weeks JC , Wong Y-N , Theriault RL , Keating NL 
Published: June 2012

Background Racial/ethnic disparities in breast cancer care are well documented. Although adjuvant trastuzumab has been shown to improve disease outcomes for women with Human Epidermal Growth Factor Receptor 2 (HER2)-positive cancers, the ‘real world’ utilization and toxicity of adjuvant trastuzumab are unknown. Because therapy involves one year of treatment and the costs of treatment are high, a risk for treatment disparity exists. We examined differences in receipt and completion of adjuvant trastuzumab by race/ethnicity, education, employment, and insurance for women diagnosed with HER2−positive breast cancer.

Methods Using the National Comprehensive Cancer Network (NCCN) Breast Cancer Outcomes Database, we identified 1,146 women with stage I-III HER-2 positive breast cancer who presented to participating NCCN institutions during 2005–2008. In multivariable logistic analyses, we assessed the effect of race/ethnicity on the likelihood of trastuzumab therapy, and among women who initiated trastuzumab, the likelihood of completing ≥ 270 days of therapy, adjusting for center, diagnosis year, age, insurance, comorbidity, education, employment, and tumor characteristics. We also examined reasons for discontinuation of therapy among those who stopped treatment prematurely.

Results Among patients eligible for this analysis, 75% women were Caucasian, 9% were African-American, and 9% were Hispanic. Most women had managed care insurance (71%) and were employed/student (52%). About one-third (36%) had a college degree and 39% had a high school education or less. Overall, most women (82%) received neo/adjuvant trastuzumab and there were no racial/ethnic differences in receipt of therapy (adjusted odds ratio [OR] 1.11, 95% confidence interval [CI] .72-1.71 for African-American and OR 1.39, 95% CI .76-2.54 for Hispanic, versus Caucasian women). Among the 769 women who initiated neo/adjuvant trastuzumab and had ≥ 365 days of follow-up, 84% completed ≥ 270 days of trastuzumab. Rates of completion were lower for African-American (72%) and Hispanic (82%) women than Caucasian women (85%). In adjusted analyses, African-American women but not Hispanic women had lower odds of completing therapy compared with Caucasian women (OR .45, 95% CI .29-.70, p=0.0003). Indemnity insurance (versus managed care) was associated with lower odds of trastuzumab completion, as was having a high school education or less (versus college education). Among the 123 women who did not complete trastuzumab, 26% stopped early for toxicity, and this occurred more frequently for African-American women than Caucasian women (50% vs. 21%), but small sample precluded a meaningful test for statistical significance.

Conclusion: Compared with Caucasian women, African-American women had similar rates of initiation of adjuvant trastuzumab but much lower rates of completion that were not explained by differences in education, employment, or insurance. Because of the significant benefits conferred by adjuvant trastuzumab therapy for HER2−positive breast cancer, interventions to assure completion of therapy could lead to improved outcomes. Further exploration of racial differences in toxicity and tolerance of therapy are also warranted.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-11-02.