title: The lack of CD34 expression in gastrointestinal stromal tumors is related to cystic degeneration following imatinib use.
abstract: OBJECTIVE
  We evaluated the characteristics of the gastrointestinal stromal tumors that showed discrepancies between their assessment using the Response Evaluation Criteria in Solid Tumor (RECIST) and Choi's criteria. We also investigated the clinical applicability of Choi's criteria to Korean gastrointestinal stromal tumor patients undergoing imatinib therapy.
  
  
  METHODS
  Patients with advanced gastrointestinal stromal tumors treated with frontline imatinib were analyzed. Computed tomography images of these patients were reviewed and genotyping for the KIT and PDGFRA genes was performed. Immunohistochemical staining of c-KIT, CD34, platelet derived growth factor receptor-alpha, platelet derived growth factor receptor-beta, AKT, P-ERK and vascular endothelial growth factor was followed.
  
  
  RESULTS
  Ninety-five patients were enrolled. When using Choi's criteria to evaluate the 61 patients who achieved at least partial response by Choi's criteria, 27 patients showed discrepancies in their response to treatment between these two sets of criteria. A lack of CD34 expression in tumors was found to be related to cystic degeneration after imatinib treatment (P=0.001). Patients who showed partial response by Choi's criteria but stable disease by RECIST criteria had a similar progression-free survival to cases who showed a partial response under both systems (P=0.951).
  
  
  CONCLUSIONS
  Gastrointestinal stromal tumors showing cystic degeneration after imatinib treatment lack CD34 expression. Choi's criteria have a clinical value in terms of the progression-free survival in Korean patients treated with imatinib.
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Cancer Research Institute, Seoul National University College of Medicine, 101 Daehangro, Chongno-gu, Seoul 110-744, Republic of Korea.
authors.forename: Youngil
authors.initials: Y
authors.lastname: Koh
authors.forename: Hee Eun
authors.initials: HE
authors.lastname: Lee
authors.forename: Do-Youn
authors.initials: DY
authors.lastname: Oh
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Se-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Se Hyung
authors.initials: SH
authors.lastname: Kim
authors.forename: Dong-Wan
authors.initials: DW
authors.lastname: Kim
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
authors.forename: Dae Seog
authors.initials: DS
authors.lastname: Heo
authors.forename: Woo-Ho
authors.initials: WH
authors.lastname: Kim
authors.forename: Yung-Jue
authors.initials: YJ
authors.lastname: Bang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000096:biosynthesis*; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000627:therapeutic use; D001549:Benzamides; D018572:Disease-Free Survival; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005838:Genotype; D006801:Humans; D000068877:Imatinib Mesylate; D007150:Immunohistochemistry / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis / Q000235:genetics; D011743:Pyrimidines / Q000009:adverse effects / Q000627:therapeutic use*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000096:biosynthesis / Q000235:genetics; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis; D055815:Young Adult
chemical_list: D018952:Antigens, CD34; D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D042461:Vascular Endothelial Growth Factor A; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha