There are treatments for carcinoid syndrome that address the underlying causes of the symptoms. In this section, you will find information about these treatments, including:
- Surgical Debulking
- Hepatic Artery Embolization, Chemoembolization, or Ligation
- Medical Therapy
- Radiotherapy
Surgical Debulking
For patients with carcinoid syndrome, surgical debulking of tumors can decrease the amount of hormones being produced by tumor cells. For some patients, this may provide some relief of symptoms. However, since it is often not possible for surgeons to remove all metastatic tumor presence, signs and symptoms of carcinoid syndrome may remain, or may return as the remaining tumor grows. Cryosurgery may sometimes be used to destroy carcinoid tumor cells in the liver when it is not possible to remove them surgically1,2,3.
Surgery can also be used to relieve intestinal obstructions caused by tumors, which may relieve abdominal pain, bleeding, or other symptoms. Some patients with cardiac disease may have surgery for valve replacement3,4.
Hepatic Artery Embolization, Chemoembolization, or Ligation2,3,5
Another means of debulking tumor presence in the liver is to cut off the supply of blood and oxygen required for tumor growth. The rationale behind this approach is that the portal vein provides 75% to 80% of the blood supply to normal liver cells, while the hepatic artery only provides 20% to 25% of the normal blood supply. In contrast, the hypervascularity of hepatic neoplasms results in their deriving almost all of their blood supply from the hepatic artery. Thus, occluding a hepatic artery will cause tumor necrosis while preserving most of the normal liver cells. In practice, this may be accomplished by injecting a hepatic artery with embolic material (which obstructs the vessel with a clot or foreign substance) or by surgical ligation of a hepatic artery. However, in time new blood vessels develop, which restores circulation to the remaining tumor cells.
In some cases, hepatic artery embolization is accompanied by the administration of chemotherapy agents. The chemotherapy acts directly to destroy tumor cells in the liver. And, by administration into a hepatic artery, chemotherapy agents are present in reduced quantities in other areas of the body and, therefore, cause a reduced incidence of toxic effects.
Medical Therapy
- Somatostatin analogues
Somatostatin analogues, such as octreotide acetate, known as Sandostatin® LAR Depot, block the release of bioactive substances from carcinoid tumors. Also, like somatostatin, Sandostatin® LAR Depot exerts direct effects on the gastrointestinal tract itself; it prolongs intestinal transit time. By doing so, it can significantly reduce severe diarrhea and flushing that are associated with excess quantities of these bioactive substances2,6.
Sandostatin® LAR Depot builds on the established efficacy of octreotide acetate by adding the long-acting release formulation. Sandostatin® LAR Depot is administered monthly, rather than daily7:
- Sandostatin® LAR Depot incorporates octreotide into microspheres of the biodegradable glucose star polymer, D,L-lactic and glycolic acids copolymer
- Slow drug release accompanies the biodegradation of the polymer ester bond through hydrolysis
- The short-acting formulation can be used for additional control of symptom flare ups
The following drugs require monitoring and possible dose adjustment when used with Sandostatin® LAR Depot: cyclosporine, insulin, oral hypoglycemic agents, beta-blockers, and bromocriptine. Octreotide has been associated with alterations in nutrient absorption, so it may have an effect on absorption of orally administered drugs. Drugs mainly metabolized by CYP3A4 and which have a low therapeutic index should be used with caution.
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Interferon-α
Interferon-α has been shown to reduce hormone production from carcinoid tumors. In about half to two-thirds of patients in clinical trials, this has been accompanied by reduction in symptoms. In a few patients, interferon-α has also reduced tumor size. (In several small trials, response rates ranged from 0% to 20%.)8,9
Interferon-α is usually administered 3 times a week, in doses of approximately 3 to 9 million units given by subcutaneous injection. Most patients experience flu-like symptoms (fever, fatigue) for a few days after administration. Other side effects, including weight loss and anemia, have also been noted2,9.
Chemotherapy2,10
In the past, chemotherapy was frequently used to try to reduce the growth of primary and metastatic carcinoid tumors. However, since chemotherapy typically produced poor results (with partial responses in no more than 10% to 20% of patients) and was associated with significant toxicity, it now has a greatly reduced role.
Radiotherapy
Radiation therapy may be used to address specific symptoms (eg, pain resulting from bone metastasis) that may be present in certain patients with carcinoid syndrome. However, it is not useful in treating metastases in the liver or other nonskeletal tissues2,9.
INDICATIONS AND USAGE
Sandostatin® LAR Depot (octreotide acetate for injectable suspension) is indicated for patients in whom initial treatment with immediate release Sandostatin® (octreotide acetate) Injection has been shown to be effective and tolerated for:
- Long-term maintenance therapy in acromegalic patients who have had inadequate response to surgery and/or radiotherapy or for whom surgery and/or radiotherapy is not an option (the goal of treatment in acromegaly is to reduce GH and IGF-1 levels to normal).
- Long-term treatment of the severe diarrhea and flushing episodes associated with metastatic carcinoid tumors.
- Long-term treatment of the profuse watery diarrhea associated with VIP-secreting tumors.
In patients with carcinoid syndrome and VIPomas, the effect of Sandostatin Injection and Sandostatin LAR Depot on tumor size, rate of growth and development of metastases has not been determined.
IMPORTANT SAFETY INFORMATION
Warnings and Precautions:
- Gallbladder abnormalities may occur: Patients should be monitored periodically.
- Glucose Metabolism: Hypoglycemia or hyperglycemia may occur. Blood glucose levels should be monitored when Sandostatin LAR Depot treatment is initiated or when the dose is altered. Antidiabetic treatment should be adjusted accordingly.
- Thyroid Function: Hypothyroidism may occur. Baseline and periodic assessment of thyroid function (TSH, total and/or free T4) is recommended.
- Cardiac Function: Bradycardia, arrhythmia, conduction abnormalities, and other EKG changes may occur. The relationship of these events to octreotide acetate is not established because many of these patients have underlying cardiac disease. Use with caution in at-risk patients.
- Nutrition: Octreotide may alter absorption of dietary fats. Monitoring of vitamin B12 levels is recommended during therapy with Sandostatin LAR Depot. Patients on total parenteral nutrition (TPN) and octreotide should have periodic monitoring of zinc levels.
Drug Interactions: The following drugs require monitoring and possible dose adjustment when used with Sandostatin LAR Depot: cyclosporine, insulin, oral hypoglycemic agents, beta-blockers, bromocriptine. Octreotide has been associated with alterations in nutrient absorption, so it may have an effect on absorption of orally administered drugs. Drugs mainly metabolized by CYP3A4 and which have a low therapeutic index should be used with caution.
Adverse Reactions: The most common adverse reactions occurring in patients receiving Sandostatin LAR Depot are:
- Acromegaly: biliary abnormalities (52%), diarrhea (36-48%), cholelithiasis (13-38%), abdominal pain or discomfort (11-29%), flatulence (26%), influenza-like symptoms (20%), constipation (19%), headache (15%), anemia (15%), hyperglycemia (15%), injection site pain (2-14%), hypertension (13%), dizziness (12%), fatigue (11%), nausea (10%), vomiting (7%), hypothyroidism (2%), hypoglycemia (2%), and goiter (2%).
- Carcinoid Tumors and VIPomas: biliary abnormalities (62%), injection site pain (20-50%), nausea (24-41%), abdominal pain (10-35%), fatigue (8-32%), headache (16-30%), hyperglycemia (27%), back pain (8-27%), constipation or vomiting (15-21%), dizziness (18-20%), sinus bradycardia (19%), pruritus (18%), URTI (10-18%), myalgia (4-18%), flatulence (9-16%), arthropathy (8-15%), rash (15%), generalized pain (4-15%), sinusitis (5-12%), conduction abnormalities (9%), hypoglycemia (4%), and arrhythmia (3%).
