When they occur in the lungs or in the gastrointestinal tract, neuroendocrine tumors may be the consequence of asbestos exposure in people who were exposed to this mineral during the last century. While they can initially be benign, neuroendocrine tumors may turn malignant in individuals with a history of asbestos exposure.
Every year, over 12,000 people in the United States are diagnosed with a neuroendocrine tumor. There are approximately 175,000 individuals living with this diagnosis throughout the country at the moment. Within recent years, the number of people who receive a neuroendocrine tumor diagnosis has been increasing, as more and more awareness has been raised concerning this condition. Additionally, the medical technology used to diagnose neuroendocrine tumors, such as endoscopy and imaging tests, has been evolving, which resulted in a larger number of individuals receiving this diagnosis. While there is no known cause of neuroendocrine tumors, asbestos exposure was found to contribute to their development.
What are neuroendocrine tumors?
Occurring in the cells of the endocrine or nervous system, neuroendocrine tumors are neoplasms, abnormal growths of tissue which most commonly develop on organs such as the small intestine, the lungs, the appendix, the rectum, and the pancreas. However, they can occur on any part of the body, since the endocrine and nervous systems extend throughout the entire human body. There are multiple types of neuroendocrine tumors, some of the most frequently diagnosed being:
- adrenal cancer: a malignant disease which begins developing in one or both of the small glands of the kidneys, medically known as the adrenal glands, which produce hormones
- carcinoid tumors: as a type of tumors which develop slowly, carcinoid tumors can arise in several areas of the body, including the stomach, the appendix, the small intestine, the colon, the rectum, and the lungs
- Merkel cell carcinoma: this is a rare and aggressive type of skin cancer which usually occurs in the elderly and is also known as neuroendocrine carcinoma of the skin
- pancreatic neuroendocrine tumors: also known as islet cell cancers, pancreatic neuroendocrine tumors are rare and develop on the pancreas
- paraganglioma: affecting mostly people between the ages of 30 and 50, paraganglioma is a tumor which develops in certain nerve cells which are found throughout the body
- pheochromocytoma: this neuroendocrine tumor is typically benign and also develops in one or both of the adrenal glands, being able to secrete hormones which cause high blood pressure, sweating, headache, or the symptoms of a panic attack
Neuroendocrine tumors are also classified depending on whether they secrete hormones in the body. When they do, they are functional neuroendocrine tumors, and when they do not, they are referred to as nonfunctional neuroendocrine tumors. Although there is no known cause of neuroendocrine tumors, there are certain risk factors which increase the chances of a person to develop one, such as:
- multiple endocrine neoplasia: as a disease which causes the growth of tumors in the cells which produce hormones, multiple endocrine neoplasia is the result of a genetic mutation and people with a family member who has it are more likely to develop a neuroendocrine tumor in their pancreas
- Von Hippel-Lindau disease: this condition results in the growth of abnormal blood vessels, tumors, and cysts around various areas of the body, which places one at higher risk of developing pheochromocytoma
- tuberous sclerosis: in this condition, tumors occur in the brain, lungs, kidneys, eyes, or skin, which are usually benign, but can cause health issues such as seizures and learning problems
- neurofibromatosis: it causes tumors to grow along your nerves and skin, which increases the risk of a neuroendocrine tumor developing
- asbestos exposure: if asbestos fibers reach the organs which can be affected by a neuroendocrine tumor, they may lead to the occurrence of one in the lungs, the small intestine, the stomach, the colon, or the rectum
- age: carcinoid tumors are more common in people between the ages of 50 and 60, pheochromocytoma is more likely to occur in individuals between the ages of 40 and 60, whereas Merkel cell cancer usually develops in people over 70
- gender: men are more susceptible to developing pheochromocytoma and Merkel cell cancer, whereas women are more likely to receive a carcinoid tumor diagnosis
- a weak immune system: people who have a poor immune system, regardless of the reason, are more prone to developing a type of neuroendocrine tumor
- exposure to the sun: too much exposure to the sun may lead to the occurrence of Merkel cell carcinoma, which affects the skin
While the symptoms of neuroendocrine tumors vary greatly, depending on their location and on whether they are benign or malignant, some of the most common signs include the following:
- redness in the face or neck
- shortness of breath
- heart palpitations
- high blood pressure
- a lingering cough
- swelling in the feet and ankles
- discolored patches of skin
- frequent urination
- increased appetite and thirst
Neuroendocrine tumors by location in the body
As previously mentioned, neuroendocrine tumors can develop on any organ, as the endocrine and nervous systems exist throughout the entire body. Nevertheless, they are more common in certain organs and areas of the body. The following are the most frequently affected organs by neuroendocrine tumors.
- The gastrointestinal tract. Neuroendocrine tumors that develop in the digestive system are also referred to as carcinoid tumors since they are usually malignant. They can occur in the small intestine (39%), the rectum (15%), the appendix (7%), the colon (5%), and the stomach (4%). The vast majority of neuroendocrine tumors affect the gastrointestinal tract. If they are functional, they will secrete high levels of hormones such as neuropeptides and amines. Approximately 40% of neuroendocrine tumors which develop in the digestive system are functional.
- The lungs. The second most common organs which may be affected by neuroendocrine tumors are the lungs. Approximately 30% of neuroendocrine tumors occur in the bronchial system of the lungs. There are 3 types of neuroendocrine tumors of the lungs: typical, atypical, and poorly differentiated neuroendocrine carcinomas. If they are functional, neuroendocrine tumors occurring in the lungs will secrete excessive amounts of hormones in the body, which will result in the patient experiencing symptoms.
- The pancreas. Approximately 7% of neuroendocrine tumors develop in the pancreas, which is a gland located in the abdomen between the stomach and the spine. It is worthy of note that a pancreas neuroendocrine tumor is different from the pancreas adenocarcinoma. The former develops in the islets of Langerhans in the endocrine component of the pancreas, whereas the latter occurs in the exocrine component of the organ.
Neuroendocrine tumors and asbestos exposure
Asbestos exposure, which occurs when a person inhales or ingests asbestos fibers from the air, can lead to the development of a neuroendocrine tumor in the lungs or in the gastrointestinal tract. In a study published in the medical journal Annals of Occupational Hygiene in 2014, asbestos fibers were found in 25% of people with pulmonary carcinoid tumors.
A small percentage of lung cancers are neuroendocrine tumors. Nonetheless, they are likely to occur in people with a history of occupational or military asbestos exposure, since the amount of asbestos fibers in their body is often large. Because asbestos fibers can travel through the bloodstream following inhalation or ingestion, they can easily reach the lungs or one of the organs within the gastrointestinal tract. There, they will gradually cause inflammation and tissue scarring which can, in turn, lead to the occurrence of a neuroendocrine tumor. It is important to note that it may take between 20 and 50 years for a neuroendocrine tumor to develop in individuals who were exposed to asbestos.
In people with a history of asbestos exposure, a neuroendocrine tumor can develop on the following organs:
Oftentimes, neuroendocrine tumors which develop as a consequence of asbestos exposure are malignant, since asbestos fibers are a known human carcinogen and thereby very harmful to the human body. If you have a history of asbestos exposure, it is highly recommended to undergo regular medical examination, as you may have a neuroendocrine tumor and experience no symptoms in the early phase of the disease. While your neuroendocrine tumor may initially be benign, it can turn malignant over the years because of the carcinogenic asbestos fibers within it.
People with neuroendocrine tumors may be eligible for compensation