We report here a very rare case of six synchronous primary colorectal cancers. A 78-year-old male was admitted to our department for further examinations and treatment of rectal bleeding, anemia and general fatigue. Colonoscopy revealed an ulcerative and localized type tumor in the rectosigmoid. The tumor obstructed the lumen, and further observation of the oral side was not possible. The patient was preoperatively diagnosed as rectosigmoid cancer, and was operated. Besides the preoperatively diagnosed cancer, three tumors were detected in the sigmoid, descending and transverse colons, respectively. Subtotal colectomy was performed. Pathological examination revealed a total of six cancers. Such as in this case, advanced cancer of the distal colon sometimes prevents accurate diagnosis of the coexisting tumor in the proximal portion. Therefore, in this condition, we believe that careful palpation during the operation and intraoperative colonoscopy will contribute to accurate diagnosis and improving the prognosis of patients with synchronous multiple primary colorectal cancers.
