Evaluation of appendectomy as a potential risk factor for immune checkpoint inhibitor-associated enterocolitis.

ABSTRACT

Aims: The relationship between appendectomy and immune checkpoint inhibitor (ICI) enterocolitis was explored. Methods: Patients who began ICIs between July 2010 and September 2020 (n = 10,907) were included. The exposure group included patients with evidence of appendectomy prior to ICIs in operative notes (n = 380). The control group included patients with evidence of normal appendix in radiologic reports (n = 3602). ICI enterocolitis was defined as histopathologic evidence of colitis or enteritis attributed to ICIs. The association between appendectomy and ICI enterocolitis was characterized by multivariate logistic regression. Results: 248 patients (6.2%) developed ICI enterocolitis. The odds of ICI enterocolitis were similar among those with prior appendectomy and those without appendectomy (adjusted odds ratio 0.82; 95% CI 0.49-1.36; p = 0.449). Conclusion: No association was found between prior appendectomy and ICI enterocolitis.

Immune checkpoint inhibitors (ICIs) are a form of cancer treatment that 'unleash the brakes' on the body's immune system. One common and sometimes serious side effect of this type of drug is gut inflammation. Studies have shown that appendectomy, or surgical removal of the appendix, lowers the risk of inflammatory bowel disease, which is another cause of gut inflammation. This research assessed whether appendectomy reduces the risk of gut inflammation caused by ICIs. Patients on ICIs for cancer with and without prior appendectomy were identified. The rates of gut inflammation caused by ICIs between these two groups were compared and the rates of this side effect were similar. This suggests that appendectomy does not reduce the risk of gut inflammation caused by ICIs.