title: Synchronous gastrointestinal stromal tumors (GIST) and other primary cancers: case series of a single institution experience.
abstract: BACKGROUND
  Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasm affecting the gastrointestinal tract. The incidental occurrence of mesenchymal tumors and other primary tumors has not been well described in literature.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the clinical and pathologic features of GIST occurring synchronously with other primary tumors.
  
  
  METHODS
  Forty-three patients with diagnosis of GIST treated surgically with curative intent at our institution from 1998 to 2006 were included. The patient clinical data and pathological reports were reviewed.
  
  
  RESULTS
  Of the 43 patients, there were 6 (14%) cases of synchronous GIST and other primary tumors discovered as coincidental findings. The synchronous GISTs analyzed were located in the stomach (50%) and small intestine (50%), size ranging from 0.7 to 7.6 cm (median 3.35 cm). Five (83%) of the concurrent primary tumors were from gastrointestinal origin and only one (17%) patient presented with concurrent breast cancer and GIST. The synchronous GISTs immunofenotype shows positivity for CD117 and CD34 (100%), smooth-muscle actin (SMA) (67%), S100 (50%) and desmin (33%). Whereas staining for cytokeratin AE1/AE3 and PDGF were all negative. According to GIST risk category for aggressive behavior three were classified as very low, one intermediate and two high.
  
  
  CONCLUSIONS
  The synchronous occurrence of GISTs and other primary neoplasm is not an uncommon entity and usually they are discovery incidentally. Epithelial tumors of the gastrointestinal tract are the most associated with concomitant GISTs. Further studies are required to clarify the molecular and genetic mechanisms of carcinogenesis and progression associating GIST and synchronous tumors.
authors.affiliation: Department of Medical Oncology, Pontifical Catholic University of Rio Grande do Sul, São Lucas Hospital, 6690 Ipiranga av, 90610-000 Porto Alegre, Brazil. sheilasf@terra.com.br
authors.forename: Sheila S
authors.initials: SS
authors.lastname: Ferreira
authors.forename: Gustavo
authors.initials: G
authors.lastname: Werutsky
authors.forename: Marcelo Garcia
authors.initials: MG
authors.lastname: Toneto
authors.forename: Jarcedy Machado
authors.initials: JM
authors.lastname: Alves
authors.forename: Christina Duarte
authors.initials: CD
authors.lastname: Piantá
authors.forename: Raquel Cristine
authors.initials: RC
authors.lastname: Breunig
authors.forename: Adriana
authors.initials: A
authors.lastname: Brondani da Rocha
authors.forename: Ivana
authors.initials: I
authors.lastname: Grivicich
authors.forename: Bernardo
authors.initials: B
authors.lastname: Garicochea
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D015331:Cohort Studies; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult