Neoadjuvant treatment has become the standard of care for locally advanced gastrointestinal carcinoma, hence,
the pathologist increasingly encounters treated primary and metastatic colorectal tumors. The pathologic assessment of
therapeutic response and evaluation of residual disease is important because the histologic response to therapy or tumor
response grade (TRG) has been shown to correlate with survival. Therefore, it is important for the pathologist to be
familiar with the changes seen in colorectal cancer and metastatic colorectal cancer after neoadjuvant therapy. This review
discusses the treatment effects seen in colon, rectal and liver resections including lymph nodes and the evaluation of
residual tumor tissue in these specimens.