Immunotherapy-induced colitis in metastatic colorectal cancer: a systematic review and meta-analysis

Colorectal cancer (CRC) presents significant mortality risks, underscoring the urgency of timely diagnosis and intervention. Advanced stages of CRC are managed through chemotherapy, targeted therapy, immunotherapy, radiotherapy, and surgery. Immunotherapy, while effective in bolstering the immune system against cancer cells, often carries toxic side effects, including colitis. This study aimed to evaluate the incidence of colitis in patients with metastatic CRC (mCRC) undergoing various immunotherapy treatments. Through a systematic search of Google Scholar and PubMed databases from inception until November 2023, nine relevant studies were identified. Subgroup analyses revealed a higher incidence of colitis, particularly in patients treated with anti-cytotoxic T-lymphocyte-associated molecule-4 (anti-CTLA-4) and combination therapies compared to monotherapy with programmed cell death receptor-1 (PD-1) or programmed cell death ligand receptor-1 (PDL-1) inhibitors. Notably, naive-treated metastatic CRC patients exhibited elevated colitis incidences compared to those previously treated. In conclusion, anti-CTLA-4 and combination therapies, such as nivolumab plus ipilimumab, were associated with increased colitis occurrences in metastatic CRC patients, highlighting the need for vigilant monitoring and management strategies, especially in immunotherapy-naive individuals.