Page 13 - Cancer Update Spring 2019 Vol. 8 Issue 1

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WHAT ARE NEUROENDOCRINE TUMORS?
In the United States, approximately 15,000
to 25,000 people are diagnosed with a neuroendocrine cancer each year. Although neuroendocrine tumors (NETs) represent less than 2% of all diagnosed malignancies, their unique hormone-secreting properties and the propensity for metastasis make them important to find and treat.
Types of neuroendocrine tumors
NETs are rare cancers that originate from hormone-producing cells located throughout the body. NETs can develop at a variety of sites and are extremely heterogeneous, both in the tumor biology and the clinical presentation (see Figure 1).
The most common NETs originate in the gastrointestinal system and lung, totaling about
12,000 cases per year. Low- and intermediate- grade tumors typically present with a well- differentiated cellular architecture with cancer cells that look normal and tend to grow slowly. High-grade tumors, known as neuroendocrine carcinomas, tend to be poorly differentiated. Poorly differentiated NETs are usually malignant and have a poor prognosis.
Diagnosis of these NETs relies on evaluation of multiple variables, including clinical symptoms, hormone levels, diagnostic imaging, and pathology results. The clinical judgment of
an experienced multidisciplinary team is important at diagnosis because some tumors with a well-differentiated appearance can be highly aggressive.
Figure 1. Anatomical Distribution of Neuroendocrine Tumors
= Primary (% occurrence)
= Metastasis (Liver > Lung > Bone)
Lung – Bronchus (20 - 25%)
Pancreas (17 - 20%) Small Intestine (55%)
Rectum/Colon (<5%)
Other (<3%)
– Thyroid
– Adrenal/Pheo/Parag – Cervix/Ovary