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:
- The Role of Surgery
- Effectiveness
- Transsphenoidal Surgery: The Procedure
- Biochemical Cure After Surgery
- Options for Patients Whose Surgery Fails
The Role of Surgery
The goals of surgery, as with all acromegaly therapies, include normalizing GH and IGF-1, eliminating mass effect from the tumor, and alleviating associated morbidities. Additional goals of surgery include preserving normal pituitary function, preventing recurrence of the tumor, and obtaining tissue for analysis. Advantages of surgery include rapid lowering of GH and the possibility of cure. Limitations include lower success rates with larger invasive tumors and/or less experienced surgeons. The guidelines recommend that surgery be considered as the first therapeutic option in all patients with acromegaly. Patients with mass effects will require surgery on an urgent basis. For patients not eligible or unwilling to undergo surgery, medical therapy can be selected1.
Effectiveness
Several factors need to be considered in the surgical management of acromegaly1:
- Surgical resection of the adenoma when not contraindicated is the initial treatment for acromegaly. Contraindications include:
- Patients who are poor surgical or anesthesia risks because of age or poor general health
- Patients who delay surgery because they want to maintain pituitary function, eg, women who want to become pregnant
- Patients who refuse surgery
- Cure rates reach 91% in patients with small, well-defined microadenomas (size <10 mm), and surgery provides rapid symptomatic relief2
- Cure rates for patients with macroadenomas (size >10 mm), which comprise the majority of GH tumors, are only 48%2
- Relapse may occur with macroadenomas, particularly those with extrasellar growth, after an initial improvement or apparent cure because of incomplete removal of tumor tissue3
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%2,4.
Transsphenoidal Surgery: The Procedure5
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 or nose.
Translabial transsphenoidal surgery
In translabial transsphenoidal surgery, the neurosurgeon makes an incision under the upper lip and enters through the gum to access the nasal cavity and then the sphenoid sinus.
Transnasal transsphenoidal surgery
In transnasal transsphenoidal surgery, the neurosurgeon makes an incision at the back of the nose to gain direct entry into the sphenoid sinus.
The neurosurgeon may alternately choose to make a cut at the front of the nasal septum and then tunnel to the sphenoid sinus.
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 sample2. 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 tumor6.
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 remission7. In addition, the risks associated with repeat transsphenoidal surgery are significantly greater in repeat procedures than in first-time procedures8.
When surgery fails to normalize GH levels, or when the patient is not a candidate for surgery, acromegalic patients have the following options, according to AACE guidelines (PDF 93KB)1:
- Somatostatin analogues such as Sandostatin® LAR Depot (octreotide acetate for injectable suspension)
- GH receptor antagonists such as pegvisomant
- Radiation therapy
Important Safety Information
Carcinoid Syndrome:
Sandostatin® LAR Depot (octreotide acetate for injectable suspension) is indicated for long-term treatment of the severe diarrhea and flushing episodes associated with metastatic carcinoid tumors and for the long-term treatment of the profuse watery diarrhea associated with VIP-secreting tumors in patients in whom initial treatment with immediate release Sandostatin® (octreotide acetate) Injection has been shown to be effective and tolerated.
Important Safety Information:
As with immediate release Sandostatin® Injection, the most frequently reported drug-related adverse events were biliary disorders (62%), gastrointestinal disorders (14% to 38%), and injection-site pain (20% to 50%). Hypoglycemia (4%), hyperglycemia (27%), sinus bradycardia (19%), conduction abnormalities (9%), and arrhythmias (3%) have been reported.
The controlled clinical trials that support the marketing clearance for Sandostatin® LAR Depot did not include determination of effect on tumor size or rate of growth. Sandostatin® LAR Depot is not indicated for tumor shrinkage.
Acromegaly
Sandostatin® LAR Depot (octreotide acetate for injectable suspension) is indicated for long-term maintenance therapy in acromegalic patients who have had an 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.
Important Safety Information:
As with immediate release Sandostatin® Injection, the most frequently reported drug-related adverse events were biliary disorders (52%), gastrointestinal disorders (7% to 36%), and injection-site pain (2% to 11%). Hypoglycemia (2%), hyperglycemia (15%), and hypothyroidism (2%) have been reported. While not measured in acromegalic patients receiving Sandostatin® LAR Depot, ECG changes have been reported in patients receiving immediate release Sandostatin® Injection; the degree to which these abnormalities are related to octreotide acetate is not clear, as many acromegalics have cardiovascular disease. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.
