Disaggregating Pacific Islanders and major Asian subpopulations to reveal hidden breast cancer disparities.

80 Background: The Asian American, Native Hawaiian, and Other Pacific Islander (AA/NHPI) population is the fastest growing and most socioeconomically heterogeneous racial/ethnic group in the US. AA/NHPI breast cancer outcomes are often reported as superior to Non-Hispanic Whites (NHW) however evidence suggests aggregating AA/NHPI masks disparities among subpopulations. As NHPI is often ignored as one of five official US races, this study aims to disaggregate AA and NHPI to unmask breast cancer disparities. Methods: An IRB exempt, retrospective cohort study using the National Cancer Database was conducted for women diagnosed with breast cancer in 2004-2016. AA and NHPI patients were compared with the majority NHW group. AA was separated into pertinent geographical origins: East Asian (EA; Chinese, Japanese, Korean), South Asian (SA; Indian, Pakistani), and Southeast Asian (SEA; Filipino, Vietnamese, Laotian, Hmong, Cambodian). Descriptive statistics were used. Logistic and Cox proportional hazard regressions assessed adjusted Odds Ratios (aORs) and adjusted Hazards Ratios (aHR), respectively, with 95% confidence intervals (95%CI). Analyses were adjusted for patient factors (age, insurance, income, rural/urban, education, hospital region, hospital distance, Deyo comorbidity score) and cancer characteristics (grade, stage, metastases, diagnosis year, hormone status). Results: Of 2,073,822 women there were 28,311 EA, 13,259 SA, 21,645 SEA, 5,375 NHPI, and 2,005,232 NHW. The median age was 62 years with median 66 month follow-up. Compared to NHW (9.6%), presentation with late-stage disease (Stage III/IV) was higher in NHPI (12%), SA (12%), and SEA (11%), but not EA (7.5%). On adjusted analysis (Table), EA was the only group with a statistical difference from NHW with aOR=0.85 (95%CI=0.76-0.94). Kaplan-Meier test for overall survival (OS) showed differences between ethnic/racial groups with NHPI having worse OS than AA subpopulations (p<0.0001). On adjusted analysis (Table), all AA subpopulations had lower risk of death compared to NHW: EA (aHR=0.69; 95%CI=0.64-0.74), SA (aHR=0.65; 95CI=0.59-0.71), and SEA (aHR=0.78; 95%CI=0.73-0.84) however the NHPI group had a greater risk of death (aHR=1.14; 95%CI=1.02-1.28). Conclusions: NHPI women with breast cancer have worse outcomes compared to NHW. This is masked by superior AA outcomes when aggregated. The continual improper aggregation of AA with NHPI downplays NHPI cancer disparities. Proper disaggregation of NHPI from AA warrants greater attention.[Table: see text]