Racial/ethnic disparities in time to initial treatment among patients with newly diagnosed breast cancer in a vertically integrated healthcare system.

202 Background: Previous work shows that Black patients, compared with other racial/ethnic groups, consistently experience delays in initial cancer treatment, regardless of socioeconomic status. This study examines variation in time to initial treatment (TTI) for breast cancer by race/ethnicity. Methods: We conducted a cross-sectional study using data from the KPSC Cancer Registry for patients with newly diagnosed breast cancer from 2010–2018. TTI is reported in median days. P-values are derived from Wilcoxon rank sum tests, comparing each racial/ethnic group to White patients. Results: We identified 21,955 newly diagnosed breast cancer patients from 2010–2018. When comparing TTI of Asian/PI, Black, and Hispanic patients with that of White patients, median difference in TTI ranged from 3-8 days longer for Stage I patients; 0-6 days longer for Stage II patients; 0-5 days longer for Stage III patients; and 1-5 days longer for Stage IV patients (Table 1). Compared to White patients, Black patients had TTI that was up to 7 median days longer for surgery and hormone therapy. For patients treated with chemotherapy, Asian/PI, Black, and Hispanic patients had slightly longer TTI (medians ranged 2-6 days) than White patients. Conclusions: In this vertically integrated system of care, patients with breast cancer from minoritized racial/ethnic groups had a slightly longer TTI than White patients. For example, the delay was up to 7 median days for surgery and hormonal therapy initiation among Black patients. Limitations of this work include lack of adjusting for confounding variables and other tumor characteristics. Additionally, it is unclear if these differences in TTI are clinically meaningful for informing survival. Given that this study was based in an integrated healthcare system, results may not be generalizable to other healthcare settings where delays in treatment may be even longer. Median time to initial treatment (days) for different racial/ethnic groups, based on initial treatment modality. White Asian/PI p Black p Hispanic p Other/Unk p Stage I (n=11,375) 36.0 39.0 0.002 44.0 <0.001 40.0 <0.001 36.0 0.89 Stage II (n=7473) 35.0 36.0 0.23 41.0 <0.001 35.0 0.22 34.5 0.74 Stage III (n=2200) 34.0 34.0 0.43 39.0 <0.001 35.0 0.006 33.0 0.72 Stage IV (n=907) 29.0 31.0 0.96 34.0 0.141 30.0 0.56 30.0 0.75 Chemotherapy (n=9513) 33.5 35.0 0.004 39.0 <0.001 35.0 <0.001 35.0 0.86 Hormone (n=14,226) 35.0 36.0 0.26 42.0 <0.001 37.0 <0.001 36.0 0.38 Radiation (n=9758) 33.0 35.0 0.004 38.0 <0.001 35.0 <0.001 34.0 0.54 Immunotherapy (n=1181) 34.0 37.0 0.14 39.0 0.003 36.0 0.077 33.0 0.61