Evaluation of breast cancer incidence in Lynch syndrome patients by MMR gene.

1541 Background: The current literature is divided as to whether or not breast cancer (BC) is a feature of Lynch syndrome (LS). The aim of this analysis was to investigate the prevalence of BC in patients with mutations in the individual mismatch repair (MMR) genes that cause LS. Methods: A retrospective review of patients’ personal and family history of cancer was performed on patients with LS-causing mutations. All patients that underwent full sequencing and/or large rearrangement testing for mutations in MLH1, MSH2, MSH6, PMS2 or EPCAM at Myriad Genetic Laboratories between September 2006 and October 2013 were included. Patients were excluded if they only had single site testing for a known LS mutation or if they were known to have a mutation in BRCA1 or BRCA2. A Pearson chi-square test was performed to determine if the prevalence of breast cancer was significantly different among individual MMR genes. Exact confidence limits for binomial proportions were then computed. Results: A total of 5,638 patien...