Crohn's Disease-associated Cancer.

With the accumulation of long-term cases of Crohn's disease (CD), CD-associated cancers are increasing. There are regional differences in the tumor location and histological type of CD-associated cancers; in Western countries, right-sided colon cancer occurs frequently, and squamous cell carcinoma is more common, whereas in Japan, anorectal cancer accounts for more than 80% of cases, and the majority are mucinous carcinoma. The prognosis of CD-associated colon cancer is comparable to that of sporadic colon cancer, but CD-associated anorectal cancer has a significantly worse prognosis than sporadic rectal cancer. Early diagnosis is important to improve prognosis, and so it is necessary to establish cancer surveillance that combines colonoscopy and examination under anesthesia with appropriate imaging diagnostics. While surgical resection is the fundamental treatment, there are no standards for surgical procedures, and there is no clear evidence regarding chemotherapy or radiotherapy. CD-associated anorectal cancer clearly has a higher local recurrence rate, therefore thorough local control is the key to improving prognosis. Because CD-associated cancers in Japan have different backgrounds from those in Western countries, it is necessary to establish original diagnostic and treatment strategies. [ABSTRACT FROM AUTHOR]