Are there disparities in adjuvant treatment of HER2 positive breast cancer patients by age, race/ethnicity, and socioeconomic status?

Abstract

e12512 Background: Standard adjuvant therapy for HER2-positive female breast cancer patients who are estrogen receptor (ER) positive is chemotherapy, trastuzumab, and endocrine therapy. Some studies report disparities in receipt of adjuvant treatment based on race/ethnicity, age, and socioeconomic status (SES). This study assessed the likelihood of receipt of adjuvant chemotherapy and endocrine therapy (C+E) versus endocrine therapy (E) alone by race/ethnicity, age, and SES in the ER+/PR+/HER- and ER+/PR+/HER+ subtypes. These subtypes differ only by HER2 status. Methods: We identified 86,666 cases of stages 1-3 ER+/PR+/HER- (n=74,422) and ER+/PR+/HER+ (n=12,244) breast cancer diagnosed between January, 2000 and December, 2010 from the California Cancer Registry. Logistic regression evaluating the odds of receipt of C+E versus E alone adjusting for age, race/ethnicity, SES, grade, and year of diagnosis was conducted separately for each stage and subtype. Odds Ratios (OR) and 95% confidence intervals were reported. Results: For both subtypes in all stages, patients over age 70 were less likely to receive C+E. Stage 1 ER+/PR+/HER-: Blacks were less likely to receive C+E (OR=0.77;0.59,0.99). The opposite was true for Hispanics (OR=1.31;1.15, 1.50) and Asians (API) (OR=1.25; 1.10;1.43). Stage 1 ER+/PR+/HER+:Hispanics were more likely (OR=1.67;1.24,2.24) to receive C+E while patients in the lowest SES category were less likely to receive C+E. Stage 2: ER+/PR+/HER-:Hispanics were more likely to receive C+E (OR=1.40;1.22,1.59) Stage 2: ER+/PR+/HER+:There were no treatment differences among race or SES. Stage 3: ER+/PR+/HER-:APIs were more likely (OR=1.87;1.19,2.94) to receive C+E. Stage 3: ER+/PR+/HER+:Patients in the lowest SES category were more likely to receive C+E (OR=2.97;1.29,6.87). Conclusions: Based on this investigation of a racially diverse population, there is no striking disparity in receipt of adjuvant treatment by race/ethnicity or SES. However there are some differences among the stages and subtypes. Patients over 70 are less likely to receive chemo and endocrine therapy for the subtypes studied.