Supplemental data for "Impact of Chemotherapy Exposure on Tumor Mutation Burden in Advanced Colorectal Cancer"

In this study, comprehensive genomic profiling of advanced colorectal cancer revealed an association between the number of prior chemotherapy regimens and tumor mutation burden. MSS TMB-high cases were not driven by polymerase gene alterations, suggesting that treatment exposure may be associated with mutational accumulation. These findings indicate that TMB should be interpreted in the context of therapeutic history, as elevated TMB may not necessarily reflect intrinsic tumor biology or predict sensitivity to immune　checkpoint inhibitors.