Pharmacoepidemiology
Temporal Treatment Patterns and Disparities By Race and Ethnicity in Management of Patients Diagnosed with Triple Negative Breast Cancer in United States: A Surveillance, Epidemiology, and End Results-Medicare Study Kehinde Adeyemi* Farzin Khosrow-Khavar Kehinde Adeyemi
Background: Chemotherapy is a mainstay treatment in management of triple negative breast cancer (TNBC). There are gaps in knowledge regarding how patients with TNBC are managed with different chemotherapy regimens in United States. Thus, the aim of this study was to examine temporal trends of first-line chemotherapy regimens among patients with TNBC in United States and to examine potential disparities by race and ethnicity.
Methods: Using Surveillance, Epidemiology, and End Results (SEER)-Medicare data sources, we identified patients ≥ 66 years with TNBC between 2010 and 2019 with follow-up to 2020. Poisson models were used to estimate annual standardized treatment initiation rates and 95% confidence intervals (CIs) for guideline recommended chemotherapy regimens within one year after TNBC diagnosis. Age-adjusted rate ratios (aRR) and 95% CIs were estimated to compare chemotherapy initiation rates by race and ethnicity.
Results: Among 11,496 patients with TNBC, 53.3% initiated chemotherapy. The median age was 74 years, 73.4% of patients were Non-Hispanic White (NHW), and 91.6% were diagnosed with locoregional TNBC. The most common first-line chemotherapy regimens were docetaxel with cyclophosphamide (TC; 33.7%) and doxorubicin with cyclophosphamide followed by paclitaxel (AC-P; 18.7%). The rate of initiation with AC-P increased between 2010-2020 while it remained constant for other chemotherapy regimens. Non-Hispanic Black (NHB) and Hispanic patients were less likely than NHW patients to initiate any chemotherapy (aRR: 0.89, 95% CI: 0.81-0.99 and aRR: 0.83, 95% CI: 0.72-0.95 respectively) including TC and AC-P.
Conclusion: In this study, we found a temporal increase in rate of first-line treatment with AC-P among patients with TNBC. NHB and Hispanic patients were less likely to initiate chemotherapy, including TC and AC-P, compared with NHW patients. Further research is needed to understand the determinants of disparities in TNBC chemotherapy by race and ethnicity.