title: Defective DNA mismatch repair in long-term (> or =3 years) survivors with pancreatic cancer.
abstract: OBJECTIVE
  Defective DNA mismatch repair (MMR) in pancreatic cancer, reported in up to 13% of sporadic pancreatic cancers, may predict a good prognosis. To determine if long-term survival in pancreatic cancer could be attributed to defective DNA MMR, we ascertained its prevalence in 35 pancreatic cancer patients who survived > or =3 years after surgery.
  
  
  METHODS
  We performed immunohistochemistry (IHC) for MMR proteins hMLH1, hMSH2, and hMSH6 in all 35 tumors and microsatellite instability (MSI) studies in 34/35 tumors using 10 microsatellite markers in paired normal and tumor DNA. Defective DNA MMR was defined as absence of protein expression on IHC and/or MSI in > or =30% of markers studied.
  
  
  RESULTS
  On IHC, 3/35 (8.6%) tumors had defective DNA MMR. All 3 had absent expression of a DNA MMR protein (hMLH1 in 2 and hMSH2) and 2/3 also had MSI; the third could not be tested. Definitely 2, and probably all 3 patients had hereditary nonpolyposis colon cancer as determined by clinical and genetic profiles.
  
  
  CONCLUSIONS
  Defective DNA MMR is uncommon in long-term survivors of pancreatic cancer and does not account for the survival benefit in those with sporadic pancreatic cancer.
authors.affiliation: Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Maple
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Smyrk
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Boardman
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Johnson
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Thibodeau
authors.forename: Suresh T
authors.initials: ST
authors.lastname: Chari
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000601:surgery; D000328:Adult; D000368:Aged; D020137:Base Pair Mismatch / Q000235:genetics; D018276:Carcinoma, Medullary / Q000235:genetics / Q000401:mortality / Q000473:pathology / Q000601:surgery; D002352:Carrier Proteins; D004260:DNA Repair / Q000502:physiology; D045643:DNA Repair Enzymes / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000601:surgery; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D015996:Survival Rate
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes