Anorectal cancer surveillance in Crohn's disease

Objectives: One of the characteristics of colorectal cancer complicating Crohn's disease (CD) in the Japanese population is that it frequently occurs in the lower anorectal site. This study aimed to examine CD patients biopsied in the lower anorectal sites to investigate the significance and problems associated with this method of cancer surveillance. Methods: Among 116 patients with CD duration of ≥10 years, we examined patients diagnosed with cancer using histological examination of the lower anorectal site (287 times). We also evaluated the detection rates of cancer and atypical cells using this method.Results: Of the 116 patients, neoplastic lesions were detected through biopsy in 22 (19.0%), of which 18 had carcinomas and 4 had atypical cells. The clinicopathological traits of the cancer patients were early-age onset and chronic disease duration of CD before cancer diagnosis. Histologic findings were characterized by a high frequency of poorly differentiated adenocarcinoma and mucinous carcinoma. The 18 patients with cancer were assigned to groups A and B depending on the presence or absence of cancer-related symptoms, and their characteristics were compared. Of these, 5 patients whose cancer was detected without symptoms (group A) had better prognosis than those detected with symptoms (group B) based on survival curves. We next examined 103 patients for surveillance after excluding 13 patients who were diagnosed with cancer-related symptoms from the 116 patients and found a 5.8% (6 patients) detection rate of cancer and atypical cells.Conclusions: Our results suggest the effectiveness of transanal histological testing for the surveillance of anorectal cancer with CD.