Patient characteristics and health system factors associated with adjuvant radiation therapy receipt in older women with early-stage endometrial cancer
Among women with early-stage endometrial cancer (EC), age, stage, grade, and histology are used to determine fitness for adjuvant radiation therapy (RT) administration. We examined non-cancer factors associated with adjuvant RT receipt in older women with early-stage EC. Using data from the Surveillance Epidemiology and End Results cancer registry program linked with Medicare claims, we identified 25,654 women (aged ≥66 years) diagnosed with first primary stage I-II EC during 2004-2017 who underwent a hysterectomy. Diagnosis and procedure codes were used to identify adjuvant RT claims filed for the seven-month period post-hysterectomy. Multivariable log-binomial regression was used to estimate adjuvant RT prevalence associated with patient characteristics and health system factors after adjustment for age, frailty, and endometrial factors. Adjuvant RT was less commonly administered to Asian American and Pacific Islander patients than non-Hispanic White patients (Prevalence ratio [PR], 0.84; 95% confidence interval [CI], 0.73 to 0.97). Compared to women treated in the Northeast region, women treated other regions of the US were less likely to undergo adjuvant RT (PR, 0.75; 95% CI, 0.71 to 0.79). Residing in rural or high neighborhood-poverty counties was associated with lower adjuvant RT administration. Higher comorbidity score was not associated with reduced prevalence of adjuvant RT receipt; however, women with high probability of predicted probability of frailty were less likely to undergo adjuvant RT (PR, 0.67; 95% CI, 0.55 to 0.81) compared to women with low probability of frailty. Women who received lymph node assessment were more likely to undergo adjuvant RT compared to women who did not (PR, 1.43; 95% CI, 1.34 to 1.51). Women treated by a gynecologic oncologist were more likely to undergo adjuvant RT compared to women treated by a non-gynecologic oncologist (PR 1.09; 95% CI, 1.04 to 1.14). Adjuvant RT was more commonly administered to women treated in larger academic hospitals. Findings suggest that various non-cancer factors affect the delivery of adjuvant RT to older women with early-stage EC in real-world oncology practice. Advancing our understanding of factors associated with adjuvant RT administration may help expand equitable access to RT.