Outcome of incidental versus preoperatively diagnosed colorectal cancer during total proctocolectomy with ileal pouch–anal anastomosis for inflammatory bowel disease

Aim: Total proctocolectomy with ileal pouch–anal anastomosis (IPAA) is the treatment of choice for colorectal cancer (CRC) in inflammatory bowel disease. CRC may also be discovered incidentally at IPAA for other indications. We sought to determine whether incidentally found CRC at IPAA was associated with worse outcomes. Methods: Our institutional pouch registry (1983–2021) was retrospectively reviewed. Patients with CRC at pathology after IPAA were divided into two groups: a preoperative diagnosis (PreD) group and an incidental diagnosis (InD) group. Their long-term outcomes (overall survival, disease-free survival and pouch survival) were compared. Results: We included 164 patients: 53 (32%) InD and 111 (68%) PreD. There were no differences in cancer staging, differentiation and location. After a median follow-up of 11 (IQR 3–25) years for InD and 9 (IQR 3–20) years for the PreD group, deaths were 14 (26%) in the InD group and 18 (16%) in the PreD group. Pouch failures were five (9%) in the InD group and nine (8%) in the PreD group, of which two (5%) and four (4%) were cancer related. Ten-year overall survival was 94% for InD and 89% for PreD (P = 0.41), disease-free survival was 95% for InD and 90% for PreD (P = 0.685) and pouch survival was 89% for InD and 97% for PreD (P = 0.80). Pouch survival at 10 years was lower in rectal versus colon cancer (87% vs. 97%, P = 0.01). No difference was found in outcomes in handsewn versus stapled anastomoses. Conclusion: Inflammatory bowel disease patients with incidentally found CRC during IPAA appear to have similarly excellent oncological and pouch outcomes to patients with a preoperative cancer diagnosis.