Colorectal Malignancy in a Prospective Irish Inflammatory Bowel Disease Population 15 Years Since Diagnosis: Comparison with the EC-IBD Cohort

Table 3

All cancer types.

Centre	Total patients (2009)	Observed	Expected	Relative risk	Lower CI	Upper CI
Dublin	133	6	0.29	0.68	0.31	1.51
All north mean	316	5	0.90	1.72	0.72	4.10
All south mean	265	4	1.54	1.50	0.57	3.98

In cases with more than one cancer, colorectal cancer was regarded as the principal cancer diagnosis and cancers of unknown primary origin were classified as extraintestinal. Assumptions for these calculations were as follows: (1) the expected numbers were calculated assuming that the patients of the EC-IBD cohort have the same risk of cancer diagnosis as the general population in their respective country; (2) the EC-IBD cohort has been assembled in the period 1991–1993, and expected numbers have been collectively calculated from the contributing centres for the 15-year follow-up period; and (3) cancer incidence rates for each study centre were obtained from the ΙΑCR databases (with actual and estimated cancer incidence rates for European countries in 2008). CI = confidence interval.