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* = Presenting author

P625. Risk of cancer in patients with inflammatory bowel disease: a population-based study

A. Algaba1, I. Guerra1, A. Castaño2, G. de la Poza1, V.M. Castellano2, M. López2, F. Bermejo1, 1Hospital Universitario de Fuenlabrada, Gastroenterology, Fuenlabrada, Spain, 2Hospital Universitario de Fuenlabrada, Pathology, Fuenlabrada, Spain

Background

Several studies have reported increased rates of colorectal cancer in patients with inflammatory bowel disease (IBD) but limited data is available for extraintestinal malignancy incidence in these patients. Our aim was to determine the incidences and characteristics of intestinal and extraintestinal cancers among patients with IBD in our environment and to compare these incidences with those of the local population.

Methods

Prospective, observational, 7-year follow-up study (2004–2011) in patients with IBD who were diagnosed with cancer in our hospital. Cumulative incidence, incidence rate based on person-year of follow-up and relative risk (RR) were calculated for patients with IBD and compared with the baseline local population (this data was obtained using our hospital's tumor registry).

Results

18 of 590 patients with IBD developed cancer (cumulative incidence = 3% vs. 2% in local population; RR = 1.5; 95% CI:0.97–2.29). At the time of cancer diagnosis, the mean age of these patients was 50±12, 61% were males, 33% were being treated with thiopurines and 6% were on anti-TNF drugs. The average period from IBD diagnosis to cancer development was 71 months (IQR 21–111). The cancer incidence rate among IBD patients was 0.53% per patient-year of follow-up. The specific type of cancer and the RR compared with the local population are shown in Table 1. All patients with urinary bladder cancer diagnosis were men and all patients with breast cancer had previous family history. Colorectal cancer diagnoses were not found despite dysplasia screening by colonoscopy being performed following standard recommendations.

Table 1
LocationNHistological typeRR95% CI
Urinary bladder4Urothelial carcinoma5.231.95–13.87*
Breast3Carcinoma1.950.63–5.87
Skin31 Melanoma2.560.34–17.63
  2 Basal cell carcinomas0.260.06–1.00
Appendix2Mucinous cystadenoma36.17.92–138.4*
Stomach1Adenocarcinoma2.960.41–20.9
Pancreas1Adenocarcinoma6.010.84–40.4
Lung1Adenocarcinoma2.560.34–17.6
Liver1Hepatocellular carcinoma4.560.64–32.5
Bowel21 Neuroendocrine carcinoma of small bowel13.01.82–29.7*
  1 rectal carcinoid8.451.18–59.7*
*Significant differences (p < 0.05).

Conclusion

The overall risk of cancer did not significantly increase in our IBD patients. However, there was an increased risk of urinary bladder cancer and, with less statistical power, an increased risk of mucocele of the appendix and of neuroendocrine tumors. Although a higher RR of colorectal cancer has been described in patients with IBD, the magnitude of this risk was low in our series.