Selecting patients with young-onset colorectal cancer for mismatch repair gene analysis.
BACKGROUND
Young patients with colorectal cancer are at increased risk of carrying a germline mutation in mismatch repair (MMR) genes. This study investigated the role of clinical criteria and immunohistochemistry for MMR proteins in selecting young patients for mutation testing.


METHODS
A cohort of 56 consecutive patients with colorectal cancer aged less than 45 years were stratified into three groups based on clinical criteria: 'Amsterdam criteria', 'high risk' and 'young onset only'. Immunohistochemistry for four MMR proteins was carried out and the rate of compliance with clinical guidelines determined.


RESULTS
Tumours from 11 patients (20 per cent) had abnormal MMR protein expression, of whom eight were referred for genetic assessment. Of 21 patients (38 per cent) in total referred to the genetics unit, six MMR gene mutations were identified, all associated with abnormal immunohistochemistry.


CONCLUSIONS
MMR immunohistochemistry should be considered routine in young-onset colorectal cancer.
Department of Surgery, University Hospital Birmingham NHS Trust, Birmingham, UK. m.walker.2@bham.ac.uk
M
M
Walker
B
B
O'Sullivan
B
B
Perakath
P
P
Taniere
D
D
Cruger
D
D
Morton
D000293:Adolescent; D000328:Adult; D015179:Colorectal Neoplasms / Q000235:genetics*; D053843:DNA Mismatch Repair; D004252:DNA Mutational Analysis / Q000379:methods; D005260:Female; D006580:Genetic Carrier Screening / Q000379:methods; D018095:Germ-Line Mutation / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000235:genetics*; D018579:Patient Selection; D010375:Pedigree; D017410:Practice Guidelines as Topic; D012307:Risk Factors