The appendix is found attached to the large intestine, and while its exact function is unknown, it is not considered to be of significant importance. Multiple forms of cancer may be classified as appendix cancer, though Neuroendocrine Tumors, Appendiceal Mucoceles, and Colonic-type Adenocarcinoma are the three most common forms. Neuroendocrine tumors account for roughly half of appendix cancers and are highly treatable when caught early. Unfortunately, Neuroendocrine tumors are often asymptomatic until metastases and are therefore typically found in the later stages. Appendiceal mucoceles are filled with a substance called mucin, which may build up to cause symptoms such as abdominal pain or blockage. This type of appendix cancer may be benign or malignant. Colonic-type Adenocarcinoma represents about 10% of appendix cancers and is often not diagnosed until an examination is performed for another reason, such as a routine colonoscopy or appendicitis.