Point: justification for Lynch syndrome screening among all patients with newly diagnosed colorectal cancer.
Either microsatellite instability testing or immunohistochemical staining for the 4 mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) should be performed on all newly diagnosed colorectal cancers. This testing will identify tumors that are microsatellite unstable, which has implications for patient prognosis and possibly treatment. In addition, it will identify patients who are more likely to have Lynch syndrome. Of every 35 colorectal cancer patients, 1 has Lynch syndrome, the most common hereditary cause of colorectal and endometrial cancers. Diagnosis of Lynch syndrome affects the medical management of the patient and their relatives, with potentially life-saving ramifications. Although screening only a subset of patients with colorectal cancer based on age at diagnosis, family history, or histologic criteria will reduce the number of screening tests necessary, it will miss a significant proportion of patients with microsatellite unstable colorectal cancer and many patients with Lynch syndrome. Given that universal screening of all patients with newly diagnosed colorectal cancer using immunohistochemistry as the initial test was recently shown to be cost-effective and comparable with other widely accepted preventive services, it is not necessary to try to reduce costs by restricting screening to a subset of patients, which leads to a reduction in the efficacy of the screening program.
Hampel
Heather
H
Division of Human Genetics, Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 43240, USA. Heather.hampel@osumc.edu
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000235:genetics; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D053843:DNA Mismatch Repair; D045643:DNA Repair Enzymes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D003657:Decision Making; D055088:Early Detection of Cancer; D005820:Genetic Testing; D006801:Humans; D007150:Immunohistochemistry; D053842:Microsatellite Instability; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D011379:Prognosis
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C501486:MLH1 protein, human; D009687:Nuclear Proteins; 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