ABSTRACT
It is not uncommon that an endoscopist should differentiate metastatic or invasive cancer to the colorectum from primary colorectal cancer with its endoscopic appearances. This study reviewed the endoscopic appearances of 7 patients who were proved to have metastatic or invasive cancers to the colorectum, both clinically and pathologically. The primary cancers were uterine cervix cancers in 3 patients, advanced gastric cancers in two, and prostatic cancer in one. The endoseopic appearances of metastatic or invasive cancer showed several characteristic features with regard to those of primary colorectal cancer, as follows. 1) Multiplicity of lesions 2) Nodular lesion with unaffected mucosa or with mild degree of erosions 3) Concentric defarmities with conical extremities and the absence of shelving margins 4) Inflammatroy lesions with mucosal hyperemia, erosion, ulceration, and bleeding, but without definite mass formation.