A primary or metastatic malignant neoplasm that affects the rectosigmoid area. Representative examples include carcinoma, lymphoma, and sarcoma. The disease is rectosigmoid junction cancer (Monarch Disease Ontology entry MONDO_0002425). Also known as: cancer of rectosigmoid junction, malignant neoplasm of rectosigmoid, malignant neoplasm of rectosigmoid junction, malignant neoplasm of the rectosigmoid junction, malignant rectosigmoid junction neoplasm, malignant rectosigmoid neoplasm, malignant rectosigmoid tumor, malignant rectosigmoid tumour.