Analysis of clinicopathological features and oncological outcomes of ulcerative colitis-associated colorectal cancer based on macroscopic classification

Purpose: Few studies have reported the association of macroscopic classification with clinicopathological characteristics and prognosis of ulcerative colitis-associated colorectal cancer (UC-CRC), unlike sporadic CRC. In this study, we aimed to clarify the clinical significance of macroscopic classification of UC-CRC. Methods: The cohort included 480 patients with UC-CRC with invasion beyond the muscularis propria treated at 43 Japanese institutions between 1983 and 2023. The patients were divided into six groups based on the macroscopic type (types 0–5), and clinicopathological features and prognoses were compared. Results: Among 480 patients, 66 (13.8%), 75 (15.6%), 116 (24.2%), 63 (13.1%), 68 (14.2%), and 92 (19.2%) had type 0–5 tumors, respectively. There were significant differences in the clinicopathological characteristics with a younger age in type 4 or 5 tumors than in type 2 tumors (p < 0.01) and a higher frequency of undifferentiated carcinomas (p < 0.01) and lymph node metastasis (p < 0.01) and more advanced depth of invasion (p < 0.01) in type 4 tumors than in type 1 or 2 tumors. Type 4 and 5 were independent risk factors for 5-year recurrence-free survival (p = 0.02; type 4 [HR: 6.35], type 5 [HR: 5.25]) and type 0, 4, and 5 for overall survival (p = 0.02; type 0 [HR: 4.51], type 4 [HR: 5.70], type 5 [HR: 4.02]). Conclusions: Type 0, 4, and 5 tumors were characteristic macroscopic types of UC-CRC and correlated with worse prognosis. Therefore, endoscopic diagnosis of the macroscopic type of UC-CRC might be helpful in determining tumor aggressiveness.