1Department of Medicine and Therapeutics, Prince of Wales Hospital, Hong Kong, China; 2Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China; 3Institute of Digestive Disease, Department of Medicine and Therapeutics, Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China; 4Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong, China; 5Department of Medicine, Tuen Mun Hospital, Hong Kong, China; 6Department of Medicine, United Christian Hospital, Hong Kong, China 7Department of Medicine, Princess Margaret Hospital, Hong Kong, China; 8Department of Medicine, Queen Elizabeth Hospital, Hong Kong, China; 9Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China; 10Department of Medicine, Tseung Kwan O Hospital, Hong Kong, China; 11Department of Medicine, Caritas Medical Centre, Hong Kong, China; 12Department of Medicine, North District Hospital, Hong Kong, China; 13Department of Medicine, Kwong Wah Hospital, Hong Kong, China; 14Department of Medicine, Alice Ho Miu Ling Nethersole Hospital, Hong Kong, China; 15Department of Medicine, Yan Chai Hospital, Hong Kong, China; and 16Department of Gastroenterology, Chelsea and Westminster Hospital, London, United Kingdom.
Studies on cancer risk in inflammatory bowel disease (IBD) have yielded inconsistent results. We conducted a population-based study to determine the risk of cancer in patients with Crohn's disease (CD) and ulcerative colitis (UC).
Using a territory-wide IBD registry in Hong Kong, we identified 2621 patients with IBD and no history of cancer from 1990 to 2016. We followed them from diagnosis until either September 2016, cancer development, proctocolectomy, or death. Standardized incidence ratios (SIRs) of overall cancer and site-specific cancers were calculated.
Of 2621 patients with IBD (1108 CD; 1603 UC; median age, 49 yr; 59.5% men) followed for 26,234 person-years, 88 patients developed cancer after IBD diagnosis. Patients with CD had an increased risk of anorectal cancers (SIR 4.11; 95% confidence interval (CI), 1.84-9.14) and hematological cancers (SIR 3.86, 95% CI, 1.61-9.27) including leukemia (SIR 5.98; 95% CI, 1.93-18.54). Nonmelanoma skin cancer was significantly increased in both CD and UC (CD: SIR 13.88; 95% CI, 1.95-98.51; UC: SIR 9.05; 95% CI, 2.26-36.19). Patients with CD had a higher risk of renal-cell carcinoma (SIR 6.89; 95% CI, 2.22-21.37), and patients with UC had a higher risk of prostate cancer (SIR 2.47; 95% CI, 1.24-4.95).
In a population-based study, Chinese patients with CD are at an increased risk of anorectal cancers and hematological cancers compared with the general population. A higher risk of nonmelanoma skin cancer was also observed in CD and UC. Cancer surveillance should be considered.