Simple SummaryDespite the advances in radiation therapy and surgical techniques that offer significant curative potential for patients with cancer, previous studies have shown a higher treatment refusal rate among Asian Americans (AA), Native Hawaiian, and other Pacific Islander (NHPI) populations. Treatment refusal has been correlated with poorer survival outcomes. In this study, we aimed to (1) estimate and compare treatment refusal rates by disaggregated AA ethnogeographic regions (based on geographic proximity of ethnicity) and NHPI individuals, (2) assess the impact of treatment refusal on overall mortality among disaggregated AA and NHPI populations in the United States adjusted for confounders, and (3) identify predictors for treatment refusal. Results from this study unmask the racial and ethnic disparities regarding cancer treatment within AA and NHPI populations and highlight the need for data disaggregation throughout the research community.AbstractDespite radiation therapy (RT) and surgery being the curative treatments, prior work demonstrated that the aggregated Asian American (AA) and Native Hawaiian and Other Pacific Islanders (NHPI) population refuse RT and surgery at a higher rates than other races. Given that AA and NHPI are distinct groups, data disaggregation is necessary to understand racial and ethnic disparities for treatment refusal. We aimed to (1) compare RT and surgery refusal rates between AA and NHPI populations, (2) assess RT and surgery refusal on overall mortality, and (3) determine predictors of refusing RT and surgery using the United States (U.S.) National Cancer Database. Adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) for treatment refusal were calculated using logistic regression. Adjusted hazard ratios (aHR) were calculated for overall survival using Cox proportional hazard models among propensity score-matched groups. The overall rate of RT refusal was 4.8% and surgery refusal was 0.8%. Compared to East AA patients, NHPI patients had the highest risk of both RT refusal (aOR = 1.38, 95%CI = 1.21–1.61) and surgery refusal (aOR = 1.28, 95%CI = 1.00–1.61). RT refusal significantly predicted higher mortality (aHR = 1.17, 95%CI = 1.08–1.27), whereas surgery refusal did not. Predictors of RT and surgery refusal were older patient age, high comorbidity index, and cancer diagnosis between 2011–2017. The results show heterogenous treatment refusal patterns among AA and NHPI populations, suggesting areas for targeted intervention.