A cancer that starts in the neuroendocrine cells.

Neuroendocrine tumors are cancers that start in the neuroendocrine cells. They can happen anywhere in the body. Neuroendocrine tumors happen most often in the lungs, appendix, small intestine, rectum and pancreas.

Symptoms depend on where the tumor starts. General symptoms include pain, swelling and feeling very tired. Some neuroendocrine tumors make hormones that cause symptoms. Symptoms of these tumors include skin flushing, diarrhea and frequent urination.

Treatment depends on the type of tumor and where it's located. Some treatments include surgery, radiation and chemotherapy.