Clinicopathological study of colorectal cancer occurring in patients with ulcerative colitis: results from a single hospital in Japan.

Background/Aims: Colorectal cancer (CRC) was first recognized as a complication of ulcerative colitis (UC) in 1925, and the increased risk has since been confirmed in a multitude of epidemiological studies. To our knowledge, however, all of these studies have been conducted in Western countries. The aim of this study was to identify the clinicopathological features of ulcerative colitis-related CRC in a consecutive series of patients at a single hospital in central Japan. Methodology: 314 (170 males, 144 females, mean age 30) consecutive patients diagnosed with ulcerative colitis were enrolled and investigated for the development of CRC. 240 patients had relapsing-remitting disease, 54 had chronic continuous disease, 16 had experienced one attack only, 2 had the acute fulminating type, and 2 were unknown. With regard to disease extension, 181 cases were of the pan-colitis type, 84 were left-sided colitis, and 42 were proctitis. Two patients (1%) had a family history of colorectal cancer and 45 (14%) were past or current smokers. Results: Colorectal cancer developed in seven patients (male to female ratio of 1:6), which was 2.2% of the total. Average age at the onset of ulcerative colitis was 28 years. Average age at the onset of cancer was 44 years, and average duration of UC at cancer onset was 192 months. Ulcerative colitis was of the pancolitis type in all cases. Three patients (43%) showed the relapse-remitting type and four (57%) the chronic continuing type. Three patients (43%) had a family history of cancer, in particular colorectal cancer in one patient (14%). None of the patients had a history of smoking. The histological type of cancer was well differentiated tubular adenocarcinoma in three patients (43%) and poorly differentiated adenocarcinoma in three patients (43%) each, and endocrine cell carcinoma in one (14%). Conclusions: In this group of Japanese patients, development of colorectal cancer was more likely to occur in patients with ulcerative colitis that was long-standing, and more extensive than left-sided colitis, particularly in those with a family history of colorectal cancer, inflammatory polyps, or dysplasia. CRCs in our patients with UC were often poorly differentiated and had a poor prognosis.