title: Nomogram to predict ypN status after chemoradiation in patients with locally advanced rectal cancer.
abstract: BACKGROUND
  Pelvic lymph node (LN) status after preoperative chemoradiotherapy (CRT) is an important indicator of oncologic outcome in patients with locally advanced rectal cancer. The purpose of this study was to develop a nomogram to predict LN status after preoperative CRT in locally advanced rectal cancer patients.
  
  
  METHODS
  The nomogram was developed in a training cohort (n=891) using logistic regression analyses and validated in a validation cohort (n=258) from a prospectively registered tumour registry at Asan Medical Center. The model was internally and externally validated for discrimination and calibration using bootstrap resampling. Model performance was evaluated by the concordance index (c-index) and calibration curve.
  
  
  RESULTS
  Pretreatment ypT stage, patient age, preCRT tumour differentiation, cN stage, lymphovascular invasion, and perineural invasion were reliable predictors of LN metastasis after preoperative CRT. The nomogram developed using these parameters had c-indices of 0.81 (training) and 0.77 (validation). The calibration plot suggested good agreement between actual and nomogram-predicted LN status after preoperative CRT.
  
  
  CONCLUSIONS
  This nomogram improves prediction of LN status after preoperative CRT in patients with locally advanced rectal cancer. It will be useful for counselling patients as well as for the design and stratification of patients in clinical trials.
authors: Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: E
authors: E
authors: Jwa
authors: Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: J H
authors: JH
authors: Kim
authors: Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: S
authors: S
authors: Han
authors: Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: J-h
authors: JH
authors: Park
authors: Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: S-B
authors: SB
authors: Lim
authors: Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: J C
authors: JC
authors: Kim
authors: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: Y S
authors: YS
authors: Hong
authors: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: T W
authors: TW
authors: Kim
authors: Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea.
authors: C S
authors: CS
authors: Yu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D016015:Logistic Models; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049451:Nomograms; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents