Colorectal cancer complicating inflammatory bowel disease: similarities and differences between Crohn's and ulcerative colitis based on three decades of experience.

Introduction: The aim of this study was to evaluate patient- and tumor-related characteristics for patients undergoing surgery for cancer complicating inflammatory bowel disease (IBD), and to assess differences between patients with Crohn's disease (CD) and ulcerative colitis (UC).
Methods: Data on all IBD patients with colon and rectal cancer (CRC) undergoing surgery between 1980 and 2007 were evaluated from prospectively maintained CRC and IBD databases. Clinical presentation, tumor stage, presence of associated dysplasia, and short- and long-term outcomes after surgery were investigated. Outcomes for IBD patients were compared with a matched group of patients with sporadic cancer.
Results: A total of 240 IBD patients (64 CD and 176 UC) with CRC were identified. At the time of CRC diagnosis, 68% UC and 26% CD patients had pancolitis. About 92% of the patients who underwent preoperative colonoscopy were noted to have suspicious lesions. Although 92.5% of the patients had a preoperative histopathologic diagnosis of cancer or dysplasia, incidental diagnosis of cancer in the resection specimen was made in 3%. Examination of the resection specimen revealed synchronous dysplasia in 48% of the patients and synchronous cancer in 12% patients. Tumor location was rectum in 36%, right colon in 28%, sigmoid colon in 17%, transverse colon 10%, and left colon in 9% of patients. CD patients were diagnosed at a more advanced cancer stage than UC. Local recurrence and overall 5-year survival rates were comparable (5.6% vs. 6.7%, P = 0.78 and 77% vs. 72%, P = 0.5, respectively) for patients with IBD and sporadic cancer.
Conclusions: Most IBD cancer can be diagnosed or suspected on the basis of endoscopic findings, biopsy of areas of active colitis, and an incidental finding of malignancy after colorectal resection for other indications is rare. CD patients present with a more advanced cancer stage. Optimal endoscopic surveillance may identify most patients with IBD cancer.