title: Correlation of immunophenotype with progression-free survival in patients with gastrointestinal stromal tumors treated with imatinib mesylate.
abstract: BACKGROUND
  The therapy for gastrointestinal stromal tumor (GIST) has been revolutionized by imatinib mesylate (IM). It is unknown whether the levels of KIT expression or the presence of CD34, smooth muscle actin (SMA), desmin, or S-100 protein predicts patient outcome from IM therapy. In the current study, the prognostic effects for KIT and other proteins (CD34, SMA, desmin, S-100) were analyzed in a series of GISTs in which protein expression was evaluated by immunohistochemical analysis (IHC).
  
  
  METHODS
  The cases of 106 patients with GIST who were uniformly treated with IM at the study institution between December 15, 2000, and January 13, 2002 were evaluated retrospectively. The association between KIT intensity, CD34, desmin, SMA, S-100 protein, and progression-free survival (PFS) was studied. Kaplan-Meier analysis and the Cox proportional hazards regression model were used for statistical analysis.
  
  
  RESULTS
  The majority of tumors arose from the stomach (37%), small intestine (35%), and colorectum (14%). KIT expression as determined by IHC was categorized as weak (10%), intermediate (32%), or strong (58%). Patient tumors expressed CD34 (75%), SMA (56%), desmin (1%), and S-100 protein (32%). Patients whose GIST had weak, intermediate, or strong KIT expression were found to have an 18-month PFS rate of 80%, 84%, and 69%, respectively (P = .30). The presence or absence of CD34, SMA, desmin, or S-100 protein did not appear to correlate with PFS after IM.
  
  
  CONCLUSIONS
  Patients with the appropriate clinical presentation and KIT-positive GIST tumors appear to benefit from IM independent of the level of KIT or the expression of CD34, SMA, desmin, or S-100 protein by IHC.
authors.affiliation: Department of Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Lucian R
authors.initials: LR
authors.lastname: Chirieac
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Trent
authors.forename: Dejka M
authors.initials: DM
authors.lastname: Steinert
authors.forename: Haesun
authors.initials: H
authors.lastname: Choi
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.forename: Jiexin
authors.initials: J
authors.lastname: Zhang
authors.forename: Shreyaskumar R
authors.initials: SR
authors.lastname: Patel
authors.forename: Robert S
authors.initials: RS
authors.lastname: Benjamin
authors.forename: A Kevin
authors.initials: AK
authors.lastname: Raymond
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides; D014408:Biomarkers, Tumor / Q000378:metabolism; D003710:Demography; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology*; D006801:Humans; D000068877:Imatinib Mesylate; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010879:Piperazines / Q000627:therapeutic use*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D011743:Pyrimidines / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit