A 70-year-old man showing positive results for a fecal occult blood test was admitted to a local hospital. He was suspected of double cancer in the cecum and duodenum. While performing ileocolic and segmental duodenal resections, he was diagnosed with cecal cancer invading the duodenum, following which he underwent surgical intervention. The tumor directly invaded the duodenum because of the mobile cecum. This case of duodenal invasion by cecal cancer is atypical.
