Invasive colon cancer derived from a small superficial depressed cancer: report of a case.

A 64-year-old male in May 1997 was diagnosed by colonoscopy and a barium enema examination as having an invasive cancer in the transverse colon. Pathologic study of the resected surgical specimen revealed a well-differentiated adenocarcinoma invading the muscularis propria. He had a colonoscopic examination in 1991 and was diagnosed as having multiple adenomas, which were endoscopically removed. After that he had annual colonoscopy or barium enema examination follow-ups. At endoscopy in February 1994, a superficial depressed cancer 6 mm in diameter had been detected. However, the cancer was not seen again in several endoscopic examinations until one in 1997. Because the location of the lesion detected in 1994 and that of the invasive carcinoma detected in 1997 were identical, it was considered that the superficial depressed cancer developed, 40 months later, to an advanced cancer. Doubling time was calculated as 8.4 months.