Reflex microsatellite instability & immunohistochemistry testing practices & follow-up of abnormal results at U.S. cancer programs

Background Abnormal results of microsatellite instability (MSI) or immunohistochemistry (IHC) testing of colorectal (CRC) tumors may suggest the presence of Lynch Syndrome (LS), a hereditary cause of CRC. Individuals with LS are at high risk for second primary cancers. Abnormal results of MSI and IHC testing influence care decisions. MSI is also a prognostic marker. The purpose of this survey-based study is to determine the current MSI and IHC testing practices and subsequent follow-up of abnormal results in U.S. cancer programs. The study aims include to: 1) explore the practice of MSI/IHC testing based on type of cancer program and the number of CRC cases accessioned during 2009 and 2) identifying the process and factors associated with follow-up of abnormal results. Routine MSI and IHC testing of CRC tumors is an emerging practice in the U.S. To date, no published studies were found that describe the practice of reflex testing for MSI and IHC abnormalities on colorectal tumors in the U.S.