Onset of ulcerative colitis and complete response during the treatment of a metastatic colon cancer: case report and literature review.

Colorectal cancer is a common cancer worldwide. Several risk factors have been described, such as age, lifestyle and family history. Inflammatory bowel diseases (IBD) are a well-recognized risk factor for the development of colorectal cancer. However, the onset of an IBD de novo in the context of the treatment of a colorectal neoplasia has not been reported before, except in the context of the treatment with immunocheckpoint inhibitors. Fifty-nine-years old man diagnosed with a metastatic colorectal cancer who received conventional treatment with chemotherapy and an antiangiogenic inhibitor. The patient had a complete response with the therapy after few cycles. Nevertheless, during the treatment, the patient presented with rectal bleeding, and was diagnosed with ulcerative colitis. Although the treatment was discontinued, tumoral complete remission is maintained. The relevance of this case lies in the concurrence of the onset of an autoimmune disease and a complete response of the malignancy. The concurrence of these events has been described previously only with immunotherapy. There are not cases reported involving chemotherapy and antiangiogenic drugs. Other causes of colitis were ruled out due to the unusual presentation of the case.