The importance of tumor studies in the initial evaluation for Lynch syndrome: a comparison of MMR positive and negative patients

Methods Patients with loss of MLH1/MSH2 on immunohistochemistry (IHC) or with microsatellite instability (MSI)high tumors were identified in our institutional LS database (February 1992–June 2010). Patients who subsequently underwent MLH1/MSH2 mutation analysis were reviewed. Patients with no identifiable MLH1 germline mutation were excluded if MLH1 promoter methylation was present or not assessed. Patients with variants of uncertain significance were also excluded. Demographics, clinical characteristics, mutational testing, and family histories of patients were analyzed.