Worsening Racial Disparities in Utilization of Intensity Modulated Radiation Therapy

The benefits of intensity modulated radiation therapy (IMRT) compared with standard 3-dimensional conformal radiation therapy have been demonstrated in many cancer sites and include decreased acute and late toxicity, improved quality of life, and opportunities for dose escalation. Limited literature suggests non-white patients may have lower utilization of IMRT. We hypothesized that as the use of IMRT has increased in recent years, racial inequities have persisted and disproportionately affect non-Hispanic Black (NHB) patients. We aim to evaluate temporal trends in IMRT utilization focusing on disparities among minoritized populations.

The National Cancer Database was queried to identify the 10 disease sites with the highest total number of cancer patients treated with definitive intent IMRT in 2017, the most recent year for which data are available. Exclusions included stage IV, age <18 years, unknown insurance status, unknown race, and palliative intent radiation. Race and ethnicity variables were combined and classified as non-Hispanic White, Hispanic, NHB, Asian, Native American/Eskimo, and Hawaiian/Pacific Islander. Multivariable logistic regression for IMRT utilization was performed for each disease site for both early (2004-2010) and contemporary (2011-2017) cohorts, adjusting for clinical and demographic covariates.

Among the 10 selected disease sites, 1,010,292 patients received radiation therapy as part of definitive treatment between 2004 and 2017. Overall IMRT utilization rates increased from 22.0% in 2004 to 57.8% in 2017. After adjustment and compared with non-Hispanic White patients, NHB patients were significantly less likely to receive IMRT in 1 of 10 disease sites in the 2004 to 2010 cohort, and 5 of 10 disease sites in the 2011 to 2017 cohort.

Despite greater awareness of racial disparities in cancer care and outcomes, this study demonstrates worsening disparities in the use of IMRT, particularly for NHB patients. These differences may exacerbate racial disparities in cancer outcomes; therefore, identification of underlying drivers of differential IMRT utilization is warranted.