title: Indeterminate Pulmonary Nodules in Colorectal Cancer: Follow-up Guidelines Based on a Risk Predictive Model.
abstract: BACKGROUND
  Chest computed tomographic (CT) scans frequently detect indeterminate pulmonary nodules (IPNs) in patients with colorectal cancer. The discovery of such nodules creates a clinical dilemma.
  
  
  OBJECTIVE
  This study was performed to identify clinical characteristics of IPNs and develop a predictive model to predict the risk of progression to pulmonary metastases in patients with colorectal cancer.
  
  
  METHODS
  We analyzed data from a prospectively collected database involving 1195 patients with colorectal carcinoma who underwent curative surgery between January 2008 and June 2010. A predictive model was constructed on the basis of the probability risk score and validated in 115 patients collected from a separate treatment period.
  
  
  RESULTS
  Of the 1195 patients who underwent a baseline staging chest computed tomography, 326 (27.2%) had IPNs. During a median follow-up of 26.7 months (interquartile range: 18.0-37.2), 74 (28.1%) showed pulmonary metastases. Five variables maintained prognostic significance after multivariate analysis: metachronous nodule, bilateral involvement, positive perineural invasion, increased number of positive lymph nodes, and rectal location of cancer. The 2-year progression-free survival rates for the very low-, low-, intermediate-, and high-risk groups were 96%, 82%, 46%, and 16%, respectively (P < 0.001), with a concordance index of 0.81 (95% confidence interval, 0.75-0.86). This model was validated in a separate patient set (P < 0.001), with a C-index of 0.83 (95% confidence interval, 0.77-0.88).
  
  
  CONCLUSIONS
  A predictive model for progression of IPNs may be clinically useful in discriminating patients who might benefit from an aggressive surveillance program and early pulmonary metastasectomies.
authors.affiliation: *Department of Surgery, Chonnam National University Hwasun Hospital and Medical School, Gwangju, Korea; and †Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Chang Hyun
authors.initials: CH
authors.lastname: Kim
authors.forename: Jung Wook
authors.initials: JW
authors.lastname: Huh
authors.forename: Hyeong Rok
authors.initials: HR
authors.lastname: Kim
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D055613:Multiple Pulmonary Nodules / Q000000981:diagnostic imaging*; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed