| [ Summary ] |
It is well established that the risk of colorectal cancer (CRC) is increased in patients with ulcerative colitis (UC) or Crohn's disease (CD) and that of small bowel cancer (SBC) is increased in those with CD. Persistent inflammation in UC has been shown to be related to carcinogenesis promotion, and longer durations of extensive colitis with persistent symptoms caused by inflammation are putative risk factors for CRC. However, the risk of CRC in patients with UC might be decreasing in recent years. In Japan, rectal and anal cancers comprised a large portion of CRC cases associated with CD, a prevalence quite different from that in Western countries. Patients with fistula cancers were significantly younger than those with CRC or SBC. There were almost no CD-specific symptoms in patients with CRC or SBC. A quarter of those patients were postoperatively diagnosed with CRC or SBC. Stage IV cancers accounted for 28 % of cases. In Japan, more than 90 % of operative procedures were limited resections, which require further evaluation. The prognosis of CRC in UC or CD was poorer than that of sporadic CRC, highlighting the need for earlier diagnosis. |