Carcinoid tumors can cause life-threatening symptoms from both hormone hypersecretion (over production) as well as tumor growth and invasion. The majority of individuals with carcinoid tumors are asymptomatic until the tumors metastasize to the liver and cause symptoms of tumor secretion. However, as the tumors grow they can cause obstructive symptoms.
Midgut and Hindgut
Individuals with midgut and (in rare cases) hindgut carcinoids may experience symptoms such as abdominal pain, nausea, and vomiting, even though diagnostic scanning shows nothing. Many individuals diagnosed with liver metastases have reported having undiagnosed abdominal pain for several years prior to their diagnosis of carcinoid.
Individuals with bronchial (lung) carcinoids most commonly present with obstructive symptoms. These symptoms may include chronic lung infection such as bronchitis and pneumonia, breathing difficulties, chest pain, and chronic cough. Less commonly, symptoms may include weakness, nausea, sweating, and Cushing’s Syndrome.
Carcinoid tumors can secrete a variety of hormones which can cause many clinical symptoms such as flushing and diarrhea. Symptoms occurring together may be classified as a syndrome. Carcinoid Syndrome occurs in approximately 10% of individuals with carcinoid tumors and is most commonly found in individuals with midgut carcinoid tumors that have metastasized to the liver. In midgut carcinoid tumors, carcinoid syndrome does not normally develop until the tumors have metastasized since the liver is able to break down the excess hormones produced by these tumors. However, once the tumors develop in the liver, the liver is no longer able to break down the excess hormones, and symptoms from them may occur. Carcinoid tumors that develop outside of the midgut can cause carcinoid syndrome without liver metastases, but rarely do.
Typical Carcinoid Syndrome
Typical Carcinoid Syndrome is the most common form of Carcinoid Syndrome and is most often caused by midgut carcinoids that have metastasized to the liver. Excess serotonin is the hormone most frequently related to Carcinoid Syndrome. The syndrome is characterized by brief episodes of flushing, diarrhea, cough, wheezing, shortness of breath, heart disease, and in rare cases, pellagra. Flushing and diarrhea are the two main symptoms that are associated with Carcinoid Syndrome. Diarrhea can be mild to severe which may lead to weight loss and lifestyle changes. The flushing may be light pink to a deep red and occurs in the face and in the nipple-line. It may be triggered by stress, alcohol, exercise and certain types of foods.
Atypical Carcinoid Syndrome
Atypical Carcinoid Syndrome is rare and is associated with foregut carcinoid tumors. It is characterized by extended episodes of flushing, headache, shortness of breath, and in rare cases, lacrimation (tears). The flushing can be deep purple and last for hours. It may be followed by increased blood flood to the limbs (arms and legs) and to the trunk (chest, stomach and back). This flush is not brought on by food.
Individuals with Carcinoid Syndrome can also experience Carcinoid Crisis which can occur spontaneously or be stress induced. A Carcinoid Crisis can be a life-threatening event that requires careful monitoring. Symptoms of a Carcinoid Crisis may include severe hypotension or hypertension, irregular and/or rapid heartbeat, wheezing, prolonged flushing, severe dyspnea (shortness of breath), and peripheral cyanosis (lack of oxygenated blood).
Carcinoid Heart Disease
Carcinoid tumors can secrete a variety of hormones and vasoactive substances such as serotonin. When these substances are released from liver metastases, the right side of the heart is exposed to them. As a result, patients may experience Carcinoid Heart Disease characterized by plaque lesions in the right side of the heart. Carcinoid Heart Disease can cause right-sided heart failure. Carcinoid Heart Disease is most common on the right side of the heart but can also occur on the left side. While serotonin production is related to development of Carcinoid Heart Disease, there is evidence of increased cardiac lesions during somatostatin analog therapy. All carcinoid cancer patients should be familiar with Carcinoid Heart Disease and discuss appropriate monitoring with their physician.
Bronchial (lung) carcinoid tumors can also secrete the adrenocorticotropic hormone (ACTH) which may cause Cushing’s Syndrome. Cushing’s Syndrome is characterized by excessive upper body weight gain, skin disorders (bruising and poor healing), baldness, and psychological disorders such as depression and anxiety.
Gastrinomas hypersecrete (over produce) gastrin causing Zollinger-Ellison Syndrome. Symptoms of Zollinger-Ellison Syndrome include diarrhea and peptic-ulcers. Patients with Zollinger-Ellison Syndrome may also develop gastric carcinoid as a result of prolonged gastrin hypersecretion.