Occult appendix pathology in patients undergoing colorectal cancer resection: is there a role for incidental appendectomy?

Purpose: The risk to benefit balance of incidental appendectomy in patients undergoing left colorectal cancer resection is unclear. The aim is to assess the proportion of histologically abnormal appendices in patients undergoing colorectal cancer resection in a unit where standard of care is appendectomy, with consent, when left-sided resection is performed. Methods: Retrospective study on prospectively collected database, conducted in a single tertiary-care centre. Overall, 717 consecutive patients undergoing colorectal cancer resection between January 2015 and June 2021 were analysed. The primary outcome was the proportion of histologically abnormal appendix specimens at incidental appendectomy. Secondary outcome was complications from incidental appendectomy. Results: Overall, 576/717(80%) patients had appendectomy at colorectal cancer surgery. In total, 234/576(41%) had a right-/extended-right hemicolectomy or sub-total colectomy which incorporates appendectomy, and 342/576(59%) had left-sided resection (left-hemicolectomy, anterior resection or abdomino-perineal excision) with incidental appendectomy. At definitive histology, 534/576(92.7%) had a normal appendix. The remaining 42/576(7.3%) showed abnormal findings, including: 14/576(2.4%) inflammatory appendix pathology, 2/576(0.3%) endometriosis, 8/576(1.4%) hyperplastic polyp, and 18/576(3.1%) appendix tumours, which encompassed 6 low-grade appendiceal mucinous neoplasms (LAMN), 3 carcinoids and 9 serrated polyps. In the 342 patients who had incidental appendectomy, 10(2.9%) had a neoplasm (2 LAMN, 3 carcinoids and 5 serrated polyps). There were no complications attributable to appendectomy. Conclusion: Patients undergoing left sided colorectal cancer surgery with an appendix in situ may benefit from a co-incidental appendectomy to treat the small proportion of synchronous neoplasms and eradicate the risk of metachronous appendicitis or a subsequent appendix tumour.