title: Independent external validation of radiotherapy and its impact on the accuracy of a nomogram for predicting survival of women with endometrial cancer.
abstract: OBJECTIVE
  To externally validate and assess the impact of radiotherapy on the accuracy of a nomogram for predicting overall survival of women with endometrial cancer.
  
  
  METHODS
  Using data from the Surveillance, Epidemiology, and End Results (SEER), we assessed the concordance indexes, the discrimination and the calibration provided by a nomogram for predicting overall survival. Patients were grouped into deciles based on their survival predictions, and the three-year overall survival in each group was compared with the mean predicted probability.
  
  
  RESULTS
  Between 1988 and 2006, 64,023 patients were analyzed and divided into two groups: 14,323 patients with adjuvant radiotherapy and 49,700 patients without adjuvant radiotherapy. Among the whole population, predicted and observed three-year overall survivals were 85.2% and 85.6% (+/-0.1%) respectively. In patients with adjuvant radiotherapy, overall survivals were 81.0% and 83.1% (+/-0.3%) and in patients without adjuvant radiotherapy, they were 86.5% and 86.3% (+/-0.2%) respectively. The concordance indexes for the whole population, in patients with radiotherapy and in patients without radiotherapy were 0.811 (+/-0.004), 0.751 (+/-0.009) and 0.803 (+/-0.006) respectively. The mean and maximal errors in patients with radiotherapy were 2.1% and 4.0% and in patients without radiotherapy 2.3% and 8.1%.
  
  
  CONCLUSIONS
  The nomogram can accurately predict three-year overall survival, whether patients undergo adjuvant radiotherapy or not. The nomogram has an improved individual discrimination when compared with the 1988 and the 2009 staging systems for endometrial cancer. It may be useful in the information processed for patients and in building surveillance timing.
authors: Department of Obstetrics and Gynaecology, APHP Hôpital Bichat, Paris, France. martin.koskas@bch.aphp.fr
authors: Martin
authors: M
authors: Koskas
authors: Sofiane
authors: S
authors: Bendifallah
authors: Dominique
authors: D
authors: Luton
authors: Emile
authors: E
authors: Darai
authors: Roman
authors: R
authors: Rouzier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016889:Endometrial Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D049451:Nomograms; D011237:Predictive Value of Tests; D018426:SEER Program