title: Inadequacy of the RECIST criteria for response evaluation in patients with malignant pleural mesothelioma.
abstract: The newly introduced Response Evaluation Criteria in Solid Tumors (RECIST), which relies on a single largest dimension of tumor rather than on the product of perpendicular diameters World Health Organisation (WHO) is intended to simplify the assessment of tumor response.
  
  
  OBJECTIVE
  Is to evaluate the performance and validity of the RECIST compared to the WHO criteria.
  
  
  METHODS
  Thirty-four consecutive patients with bidimensionally measurable malignant pleural mesothelioma (MPM) were evaluated prospectively.
  
  
  RESULTS
  In 27% (9/34) a discrepancy was found between the WHO and RECIST response evaluation 9% (3/34) concerned best responses and 18% (6/34) objective confirmed responses. In 24% (8/34) disease progression was missed by RECIST. The percentage of patients in whom one or more discordance's between WHO and RECIST were detected was 47, 88% due to underscoring by RECIST. In a subgroup of 24 MPM patients with bidimensionally measurable pleural lesions only, the discrepancy rate was 29%, always due to underscoring by RECIST. However, when in the same subgroup the modified RECIST response evaluation was used the discrepancy rate was 21% and in all cases due to underscoring by WHO.
  
  
  CONCLUSIONS
  For MPM bidimensional WHO response evaluation cannot automatically be replaced by RECIST because MPM has a non-spherical growth pattern. Our recommendation is to use the WHO criteria for bidimensional measurable lesions, RECIST for unidimensional measurable lesions and a modified RECIST response evaluation, in which the short axis perpendicular to the chest wall is used, for thickened pleural rind disease, according to the method used in the recently completed pemetrexed (Alimta) trial for MPM.
authors.affiliation: Department of Pulmonology, Erasmus University Medical Center, Rotterdam, Netherlands. r.j.vanklaveren@erasmusmc.nl
authors.forename: Rob J
authors.initials: RJ
authors.lastname: van Klaveren
authors.forename: Joachim G J V
authors.initials: JG
authors.lastname: Aerts
authors.forename: Hein
authors.initials: H
authors.lastname: de Bruin
authors.forename: Guiseppe
authors.initials: G
authors.lastname: Giaccone
authors.forename: Christian
authors.initials: C
authors.lastname: Manegold
authors.forename: Jan P
authors.initials: JP
authors.lastname: van Meerbeeck
mesh_terms: D018450:Disease Progression; D017408:Guidelines as Topic; D006801:Humans; D008654:Mesothelioma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology*; D010997:Pleural Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology*; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014944:World Health Organization