title: Improved overall survival with adjuvant radiotherapy for high-intermediate and high risk Stage I endometrial cancer.
abstract: To perform a large analysis of Stage I endometrioid-type endometrial cancer patients to determine the impact of adjuvant radiotherapy (ART) on survival.
  
  
  
  132,976 FIGO Stage I endometrioid-type endometrial cancer patients treated surgically were identified within the National Cancer Database (NCDB) comprising Commission on Cancer facilities in the United States. Patients were categorized as observation (OBS) or ART (vaginal brachytherapy, external beam radiotherapy, or both). Univariable generalized linear mixed effects models were used to estimate the odds of receiving ART, and a multivariable frailty survival model was used to estimate the instantaneous hazard of death for those receiving OBS versus ART. Due to the presence of a significant interaction, these estimates were stratified by PORTEC-based low, low-intermediate, high-intermediate, and high risk groups.
  
  
  
  104,645 (79%) underwent OBS while 28,331 (21%) received ART. Of those receiving ART, 12,913 (46%) received VBT alone, 12,857 (45%) received EBRT alone, and 2561 (9%) received EBRT+VBT. On univariable analysis, increasing stage/myometrial invasion, higher grade, older age, presence of lymphovascular space invasion, and larger tumor size predicted poorer survival (all p<0.01). On multivariable analysis, patients at high-intermediate risk and high risk experienced improved survival with ART with a hazard ratio of 0.796 (95% CI: 0.731-0.867; p<0.001) and 0.783 (95% CI: 0.693-0.885; p<0.001), respectively. There was no survival benefit for ART among patients at low or low-intermediate risk.
  
  
  
  In Stage I high-intermediate and high risk endometrioid-type endometrial cancer patients, ART significantly improves overall survival.
authors.affiliation: Department of Radiation Oncology, Stritch School of Medicine, Loyola University Chicago, United States. Electronic address: mharkenrider@lumc.edu.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Harkenrider
authors.affiliation: Health Sciences Division, Stritch School of Medicine, Loyola University Chicago, United States.
authors.forename: William
authors.initials: W
authors.lastname: Adams
authors.affiliation: Department of Radiation Oncology, Stritch School of Medicine, Loyola University Chicago, United States.
authors.forename: Alec M
authors.initials: AM
authors.lastname: Block
authors.affiliation: Department of Public Health Sciences, Stritch School of Medicine, Loyola University Chicago, United States.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kliethermes
authors.affiliation: Department of Radiation Oncology, Stritch School of Medicine, Loyola University Chicago, United States.
authors.forename: William
authors.initials: W
authors.lastname: Small
authors.affiliation: Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, United States.
authors.forename: Surbhi
authors.initials: S
authors.lastname: Grover
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods; D016889:Endometrial Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D018714:Radiotherapy, Adjuvant; D012306:Risk; D014621:Vagina / Q000528:radiation effects
keywords: Adjuvant radiotherapy; Endometrial cancer; External beam radiation therapy; Stage I; Vaginal brachytherapy