Sigmoid colon cancer presenting as complete rectal prolapse: report of a case.

We describe herein the unusual case of a 76-year-old woman who was diagnosed as having sigmoid colon cancer after presenting with complete rectal prolapse. The rectal prolapse was considered to have been caused by constipation accelerated by the colon cancer. The relationship between colorectal cancer and rectal prolapse has not yet been clarified; however, this case report suggests that rectal prolapse can present as a symptom of colorectal cancer. Thus, patients with a sudden onset of rectal prolapse should be screened for colorectal cancer.