Refusal of Radiation Results in Inferior Survival in Endometrial Cancer

Objective: We sought to understand factors associated with refusal of adjuvant radiotherapy in endometrial cancer and its impact on outcomes. Methods: Data from the National Cancer Database for patients who underwent surgery for nonmetastatic endometrial cancer between 2004 and 2015 were pooled. The Pearson chi(2) test and multivariate logistic regression analyses were used to assess demographic, clinical, and treatment factors. Inverse probability of treatment weighting was used to account for differences in baseline characteristics. Kaplan-Meier analyses and doubly-robust estimation with multivariate Cox proportional hazards modeling were used to analyze overall survival (OS). Results: We identified 4739 of 80,803 patients (5.9%) who refused radiotherapy. Factors associated with refusal were: no insurance (relative risk [RR]=1.66, P<0.01), Medicare (RR=1.42, P<0.01), living >50 miles from treatment (RR=1.34, P<0.01), Charlson-Deyo Comorbidity Scores of 1 (RR=1.16, P<0.01) or >= 2 RR=1.38, P<0.01), age above 60 years (RR=1.28, P<0.01), International Federation of Gynecology and Obstetrics (FIGO) stages IIIA (RR=1.63, P<0.01) and IIIC (RR=1.65, P<0.01) disease, papillary (RR=1.69, P<0.01) and clear cell histology (RR=1.64, P<0.01). Factors associated with radiation therapy receipt included: Hispanic race (RR=0.61, P<0.01), income >$63,000 (RR=0.89, P=0.044), undergoing chemotherapy (RR=0.17, P<0.01), FIGO stages IB (RR=0.81, P<0.01) and II (RR=0.70, P<0.01) disease, and lymphadenectomy (RR=0.79, P<0.01). After weighting, 5-year OS was significantly lower with refusal (74.3% vs. 79.7%, P<0.01). This survival decrement was maintained across FIGO stages. Conclusions: We identified characteristics associated with radiation refusal, including socioeconomic barriers, advanced disease stage, and histology. Refusal of radiotherapy conferred decreased OS across FIGO stages.