Figure 1. Occurrence of the most common types of neuroendocrine neoplasms. The occurrence of the main types of neuroendocrine tumors presented as the percentage of all NENs (315,441). GI-NENs represent the largest subgroup of NENs, followed by lung and pancreatic NENs. Subtypes not listed in this figure include NENs from the thyroid, kidney, adrenal gland, breast, prostate and skin.