These neuroendocrine tumors can occur anywhere on the body, though Riggs’ obituary does not state where hers was. As GARD points out, these tumors usually found in the digestive tract, pancreas, rectum, lungs, or appendix. NETs are also rare, according to UPMC—fewer than 2,000 new cases occur each year—and they account for less than 1% of all malignant disorders in the US.
When symptoms are present, they can include hyperglycemia and hypoglycemia, diarrhea, pain in a specific area, unexplained weight loss, changes in bowel or bladder habits, unusual bleeding or discharge, and persistent fevers, among other things. As far as treatment options go, surgery, radiation therapy, and chemotherapy can be used by itself or in conjunction with other therapies, depending on the stage of cancer and the type of NET, per the UPMC. But, while unfortunately Riggs's diagnosis was fatal, NETs are not always deadly, and survival rates depend on exactly where the tumor is located and the stage.