title: Predictive value of initial FDG-PET features for treatment response and survival in esophageal cancer patients treated with chemo-radiation therapy using a random forest classifier.
abstract: OBJECTIVE
  In oncology, texture features extracted from positron emission tomography with 18-fluorodeoxyglucose images (FDG-PET) are of increasing interest for predictive and prognostic studies, leading to several tens of features per tumor. To select the best features, the use of a random forest (RF) classifier was investigated.
  
  
  METHODS
  Sixty-five patients with an esophageal cancer treated with a combined chemo-radiation therapy were retrospectively included. All patients underwent a pretreatment whole-body FDG-PET. The patients were followed for 3 years after the end of the treatment. The response assessment was performed 1 month after the end of the therapy. Patients were classified as complete responders and non-complete responders. Sixty-one features were extracted from medical records and PET images. First, Spearman's analysis was performed to eliminate correlated features. Then, the best predictive and prognostic subsets of features were selected using a RF algorithm. These results were compared to those obtained by a Mann-Whitney U test (predictive study) and a univariate Kaplan-Meier analysis (prognostic study).
  
  
  RESULTS
  Among the 61 initial features, 28 were not correlated. From these 28 features, the best subset of complementary features found using the RF classifier to predict response was composed of 2 features: metabolic tumor volume (MTV) and homogeneity from the co-occurrence matrix. The corresponding predictive value (AUC = 0.836 ± 0.105, Se = 82 ± 9%, Sp = 91 ± 12%) was higher than the best predictive results found using the Mann-Whitney test: busyness from the gray level difference matrix (P < 0.0001, AUC = 0.810, Se = 66%, Sp = 88%). The best prognostic subset found using RF was composed of 3 features: MTV and 2 clinical features (WHO status and nutritional risk index) (AUC = 0.822 ± 0.059, Se = 79 ± 9%, Sp = 95 ± 6%), while no feature was significantly prognostic according to the Kaplan-Meier analysis.
  
  
  CONCLUSIONS
  The RF classifier can improve predictive and prognostic values compared to the Mann-Whitney U test and the univariate Kaplan-Meier survival analysis when applied to several tens of features in a limited patient database.
authors.affiliation: LITIS Quantif - EA4108, University of Rouen, Rouen, France.|Dosisoft, Cachan, France.
authors.forename: Paul
authors.identifier: http://orcid.org/0000-0002-1521-7590
authors.initials: P
authors.lastname: Desbordes
authors.affiliation: LITIS Quantif - EA4108, University of Rouen, Rouen, France.
authors.forename: Su
authors.initials: S
authors.lastname: Ruan
authors.affiliation: LITIS Quantif - EA4108, University of Rouen, Rouen, France.|Nuclear Medicine Department, Henri Becquerel Centre, Rouen, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Modzelewski
authors.affiliation: Dosisoft, Cachan, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Pineau
authors.affiliation: Dosisoft, Cachan, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Vauclin
authors.affiliation: Nuclear Medicine Department, Henri Becquerel Centre, Rouen, France.
authors.forename: Pierrick
authors.initials: P
authors.lastname: Gouel
authors.affiliation: Normandie Univ, UNIROUEN, Inserm 1245, Rouen University Hospital, Department of Hepato-gastroenterology, Rouen, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Michel
authors.affiliation: Department of Oncology, Henri Becquerel Centre, Rouen, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Di Fiore
authors.affiliation: LITIS Quantif - EA4108, University of Rouen, Rouen, France.|Nuclear Medicine Department, Henri Becquerel Centre, Rouen, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Vera
authors.affiliation: LITIS Quantif - EA4108, University of Rouen, Rouen, France.|Nuclear Medicine Department, Henri Becquerel Centre, Rouen, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gardin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D019540:Area Under Curve; D059248:Chemoradiotherapy; D018572:Disease-Free Survival; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000737:chemistry*; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D019275:Radiopharmaceuticals / Q000737:chemistry; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18