The most commonly used procedure for removal of adenoma from the pituitary is transsphenoidal surgery. In this section, you will find information about these aspects of surgery:
- Effectiveness
- Transsphenoidal Surgery: The Procedure
- Biochemical Cure After Surgery
- Options for Patients Whose Surgery Fails
Effectiveness
- Cure rates reach 91% in patients with small, well-defined microadenomas (size <10 mm), and surgery provides rapid symptomatic relief1
- Cure rates for patients with macroadenomas (size >10 mm), which comprise the majority of GH tumors, are only 48%1
- Relapse may occur with macroadenomas, particularly those with extrasellar growth, after an initial improvement or apparent cure because of incomplete removal of tumor tissue2
Risk of complications is related to tumor size and the type of surgical procedure used, the most common procedure being transsphenoidal surgery. Retrospective studies of the results of surgical treatment for acromegaly showed that the risk of postoperative complications was 5% to 8%1,3.
Transsphenoidal Surgery: The Procedure4
In this invasive procedure, a neurosurgeon approaches the pituitary through the sphenoid sinus, which is behind the nose and in front of the sella. The sella, a bony cavity at the base of the skull, houses the pituitary gland. Occasionally, large pituitary tumors may require transcranial surgery, in which the surgeon cuts into the skull (above the eye and ear) and retracts a portion of the brain to reach the tumor.
The neurosurgeon can perform transsphenoidal surgery by entering through the mouth (translabial transsphenoidal surgery) or nose (transnasal transsphenoidal surgery).
Biochemical Cure After Surgery
A retrospective study of 162 patients who underwent surgery for acromegaly between 1978 and 1996 used a stringent definition of biochemical cure: GH <2.5 ng/mL after OGTT and normalization of the IGF-1 level. The overall surgical cure rate was 57%, but was 91% for microadenomas and 48% for macroadenomas. Adjuvant radiation and/or pharmacologic therapy was given to 61 patients. The 10-year survival rate was 88%, and there was no difference in mortality between the patients in remission and a control sample1. It should be noted that surgical success in acromegaly can be dependent upon the skill and experience of the surgeon as well as the location of the tumor5.
Options for Patients Whose Surgery Fails
A second transsphenoidal surgery is rarely an option for patients whose first surgery fails. Only 15% of these patients achieve biochemical remission6. In addition, the risks associated with repeat transsphenoidal surgery are significantly greater in repeat procedures than in first-time procedures7.
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%).
