???MSI-L???, as used herein, is a term used to classify tumors as having a low frequency of MSI. When five microsatellite loci are analyzed, such as the five microsatellite loci of selected by a workshop on HNPCC at the National Cancer Institute in 1998 for use in the detection of HNPCC, a tumor is classified as MSI-L when only one of the loci shows instability.