Tumor and Patient Characteristics of Individuals with Mismatch Repair Deficient Colorectal Cancer.
OBJECTIVE
To investigate tumor and patient characteristics of individuals with mismatch repair (MMR)-deficient colorectal carcinomas.


METHODS
We immunhistochemically investigated tissue samples of 307 consecutive patients with colorectal cancer for defects in DNA MMR proteins (hMLH1, hMSH2, hMSH6, hPMS2) and those with mutations further for microsatellite instability (MSI) and BRAF V600E mutations.


RESULTS
32/308 (10.4%) tumors showed MMR deficiency. Seventy five percent (n = 24) had loss of hMLH1 and hPMS2 expression, 3% (n = 1) of hPMS2 alone, 18.8% (n = 6) of hMSH6 and hMSH2, 3% (n = 1) of hMSH2 alone. All MMR-deficient tumors showed high MSI. These tumors occurred preferably in the right-sided colon, in women and showed specific histological features. We obtained the family history of 18/32 patients; 2 (11.1%) met Amsterdam Criteria, 5 (27.8%) Bethesda Guidelines and 6 (33.3%) revised Bethesda Guidelines. BRAF V600E mutations were found in 16 (67%) of hMLH1 and none of the hMSH2 deficient tumors.


CONCLUSIONS
We suggest using immunhistochemical testing of tumor tissues with subsequent MSI analysis, which may be justified as a screening method for MMR deficiency in colorectal cancer, since it identifies patients with possibly hereditary defects and unalike response to chemotherapy.
Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
Elisabeth
E
Waldmann
Monika
M
Ferlitsch
Nicolas
N
Binder
Franz
F
Sellner
Josef
J
Karner
Birgit
B
Heinisch
Martin
M
Klimpfinger
Michael
M
Trauner
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000235:genetics; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D045643:DNA Repair Enzymes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000235:genetics; D009154:Mutation; D009386:Neoplastic Syndromes, Hereditary / Q000235:genetics* / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009687:Nuclear Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; C497172:MSH2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes