title: Lack of prognostic significance of connexin-43 labeling in a series of 46 gastrointestinal stromal tumors.
abstract: BACKGROUND
  Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors with variable malignant potential. Connexin-43 (Cx43) is the commonest gap-junction protein and has been frequently investigated in oncology. Our aim was to establish the immunohistochemical expression of Cx43 in relation to GIST location, size, Ki67 index, tumor grade and follow-up.?
  
  
  METHODS
  The study included postoperative samples of 46 patients treated for GIST in the 1999-2010 time frame. Complete clinical workup was available for 38 patients (82.6%); total surgical resection was carried out in 32 (84.2%) patients, while 13 (34.2%) patients underwent chemotherapy. Median follow-up was 40.7 months (range, 1-134). ?
  
  
  RESULTS
  The calculated incidence of GIST in our setting was 11.5 per million. Cx43 was expressed in 43/46 (93.5%) GIST cases, with a significant difference between stomach- and small intestine-derived tumors (p=0.006). Ki67 was 10% on average (range, 1-22) and was not correlated with tumor location (p=0.194). Cx43 did not show significance with regard to tumor size (p=0.264) or higher tumor grade (p=0.658), as opposed to Ki67, which significantly correlated with both (p=0.0048 and p<0.001, respectively). Cx43 and Ki67 were not significantly correlated (p=0.708). Ki67 correlated with time to recurrence (p=0.022). Ki67 >11% was taken as the indication to start imatinib chemotherapy (sensitivity 61.5%, specificity 92.0%, p=0.022). Ten (66.7%) of 15 patients with long-term (>5 years) follow-up were in remission.?
  
  
  CONCLUSIONS
  Cx43 was frequently expressed in GISTs regardless of tumor site. However, no significant relationships to histopathological parameters suggestive for prognosis were found. Further investigations might clarify the roles of Cx43 in GIST oncogenesis.
authors: Internal Medicine Department, University Hospital "Sestre Milosrdnice", Zagreb - Croatia. marcoboban@yahoo.com
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