Treatment Noncompletion and Shorter Radiation Regimens Among US Patients With Prostate Cancer: A Focus on Asian...

Higher rates of radiation therapy (RT) noncompletion may be associated with certain demographic groups in patients with prostate cancer (PC). We examined disparities in noncompletion and receipt of shorter RT regimens among disaggregated Asian American and Pacific Islander groups in the US.

We performed a retrospective cohort analysis of all patients diagnosed with localized PC (2004-2017) in the National Cancer Database who identified as White, East Asian, Southeast Asian, Pacific Islander, or South Asian who were treated with definitive RT. The two primary outcomes were 1) treatment noncompletion and 2) receiving shorter RT regimens. Regression models were adjusted for relevant sociodemographic and clinical factors.

The analytic cohort was comprised of 143,379 patients [White, n = 140,656 (98.10%); East Asian, n = 1,150 (0.80%); Southeast Asian, n = 925 (0.65%); Pacific Islander, n = 195 (0.14%); South Asian, n = 453 (0.32%)]. On multivariable analysis, Southeast Asian patients were associated with increased rate of noncompletion compared to White patients (Southeast Asian vs. White; OR: 1.55 [95% CI: 1.29-1.86], p < 0.001). Geographic region of the treatment facility within the United States also was significant, as patients from the South Atlantic (OR: 1.32 [95% CI: 1.24-1.41], p < 0.001), East North Central (OR: 1.09 [95% CI: 1.03-1.17], p = 0.007), East South Central (OR: 1.54 [95% CI: 1.41-1.68], p < 0.001), and West South Central (OR: 1.14 [95% CI: 1.04-1.24], p = 0.005) regions all had higher rates of noncompletion in comparison to patients from New England. Distance from treatment facility, presence of comorbidities, and education attainment rates significantly impacted treatment noncompletion as well. Additionally, our study reports disparities in receipt of short course RT. Pacific Islander patients had substantially higher rates of SBRT (OR: 2.60 [95% CI: 1.10-6.16], p = 0.030) compared to White patients, while Hispanic patients had lower rates of SBRT (OR: 0.48 [95% CI: 0.40-0.57], p < 0.001). Furthermore, receiving treatment in urban (OR: 0.68 [95% CI: 0.61-0.76], p < 0.001) and metro (OR: 0.50 [95% CI: 0.39-0.65], p < 0.001) facilities was associated with reduced access to SBRT than facilities in rural areas. Patients who received treatment in the Middle Atlantic (OR: 3.28 [95% CI: 2.91-3.68], p < 0.001), South Atlantic (OR: 2.72 [95% CI: 2.40-3.09], p < 0.001), East North Central (OR: 1.53 [95% CI: 1.34-1.75], p < 0.001), East South Central (OR: 3.07 [95% CI: 2.61-3.63], p < 0.001), West North Central (OR: 2.35 [95% CI: 2.02-2.75], p < 0.001), and Mountain (OR: 2.45 [95% CI: 2.01-2.97], p < 0.001) regions of the United States had significantly higher rates of SBRT compared to patients from New England.

This analysis found that Southeast Asian patients had higher rates of RT noncompletion in comparison to White patients. Additionally, disparities in SBRT access-a shorter course of RT as compared to traditional therapies-were found based on race/ethnicity and geographical factors. Our findings emphasize heterogeneous differences amongst diverse Asian American and Pacific Islander groups and support the need for further disaggregated cancer disparities research to inform targeted interventions.