Colon Adenoma After Diagnosis of Immune Checkpoint Inhibitor-mediated Colitis

Area of Science:

• Oncology
• Gastroenterology
• Immunology

Background:

• Immune checkpoint inhibitors (ICI) can cause colitis, a known indicator of immune activation associated with favorable cancer outcomes.
• The long-term effects of ICI-induced colitis on the colon's lining remain understudied.
• Understanding these long-term changes is crucial for patient management and cancer treatment strategies.

Purpose of the Study:

• To investigate the colonoscopy and histology findings in patients at least 6 months after experiencing immune checkpoint inhibitor (ICI)-mediated colitis.
• To compare the incidence of colonic polyps in patients with and without a history of ICI colitis.

Main Methods:

• Retrospective analysis of adult cancer patients diagnosed with ICI colitis between 2013 and 2020.
• Inclusion of patients with follow-up colonoscopy and a control group exposed to ICI without colitis.
• Evaluation of clinical course, treatment, endoscopic, and histologic features at diagnosis and follow-up (≥ 6 months).

Main Results:

• 51.2% of patients with ICI colitis developed new colonic polyps, including adenomas in 33.3%, at a median 12-month follow-up.
• The incidence of adenoma polyps was significantly higher in the ICI colitis group compared to the control group (p=0.041).
• Initial colitis often presented as inflammation without ulceration (76.9% endoscopic) and was treated with corticosteroids (79.4%).

Conclusions:

• Patients with a history of ICI-induced colitis show a significantly increased incidence of new colonic polyps, including adenomas, within a year.
• The findings suggest a potential long-term impact of ICI colitis on colon health, necessitating further investigation.
• Larger studies are required to refine surveillance recommendations for colonic adenomas and colorectal cancer in this patient population.