American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the most common site of metastasis for neuroendocrine tumors?

1. Lungs

2. Brain

3. Liver

4. Bone

The correct answer is: Liver

Neuroendocrine tumors (NETs) often arise in various organs, such as the pancreas, gastrointestinal tract, and lungs. When these tumors metastasize, they frequently spread to the liver. This is largely due to the vascular drainage patterns of the gastrointestinal system, which ultimately route blood to the portal circulation and then to the liver. The liver serves as a common site for metastasis because it is the first major organ that blood from these areas encounters after it leaves the primary site of the tumor. Additionally, the liver is involved in metabolizing many substances, including hormones, which can influence the growth of neuroendocrine tumors. Many NETs secrete hormones that can stimulate the growth of metastatic lesions in the liver, further supporting the prevalence of liver metastases. In contrast, other sites such as the lungs, brain, and bone are less commonly affected by metastases from neuroendocrine tumors. While these sites can still be involved depending on the specific characteristics of the tumor and its origins, they do not typically serve as primary metastastic sites for neuroendocrine tumors compared to the liver.