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* = Presenting author

P686 Characteristics of small bowel cancer associated with Crohn’s disease

M. Shinozaki*

The Institute of Medical Science, The University of Tokyo, Department of Surgery, Tokyo, Japan

Background

Population-based studies revealed that patients with Crohn’s disease (CD) have increased risk of developing small bowel cancer in comparison with the background population. However, little is known concerning to the cancer in detail, because the number of the patients are relatively small. This study aimed to clarify the clinicopathological characteristics between small bowel cancer and colorectal cancer in CD.

Methods

We performed a literature search in Ichushi (Japanese medical literature database) between 1983 and March, 2015 for small bowel cancer and colorectal cancer associated with CD. Two hundred and 65 cases were picked up, and we excluded 6 cases, because the location of the cancer was not specified clearly. Thus, 265 cases were included in this study. The cases were classified to 2 groups: patients who had small bowel cancer(s) (S group: n = 55) and those with only colorectal cancer(s) (C group: n = 210), which included perianal fistula cancer.

Results

The age at cancer diagnosis was higher in S group (53.5 (29–81); median (range)) than in C group (43 (25–89); p < 0.0001). The duration of CD was similar between S group (16 (0–40) years) and C group (15 (0–52) years; p = 0.41). The age at CD diagnosis was also higher in S group (39(12–69)) compared with C group (25 (9–84)). S group had more proportion of ileitis than C group (58% vs 10%), whereas 81% of the patients in C group had ileocolitis, and the difference was statistically significant (p < 0.0001). In S group, the cancer diagnosis was made before treatment only in 16%, and 70% of these patients had not been diagnosed before pathological examination of the resected specimen. Well differentiated and moderately differentiated adenocarcinoma occupied three-quarters of the tumour in S group, whereas only 44% in C group (p < 0.0001). On the other hand, the proportion of mucinous carcinoma was only 4% in S group, and that was 40% in C group (p < 0.0001). The clinical stage according to the Union for International Cancer Control classification was 4%/8%/39%/12%/39% (stage 0/1/2/3/4) in S group, and that was 3%/14%/35%/29%/19% in C group, and the proportion of stage 4 was significantly higher in S group. Although the resection rate was higher in S group than in C group (98% vs 87%; p = 0.0055), the prognosis was equivalent (41% were alive in S group and 44% in C group).

Conclusion

We found some differences between the 2 groups with regard to the age at cancer detection, the age at CD onset, the timing of cancer diagnosis, the histology of the cancer, and clinical stage of the cancer. We should always give attention not to miss small bowel cancer at CD operation.