Choosing the optimal approach for giant pituitary adenomas

July 25, 2024

Giant pituitary adenomas pose particular challenges for treatment. Advances in technology and understanding of the disease have greatly improved the management of these rare tumors. But experience and expertise are key to achieving optimal results.

"The treatment options for giant pituitary adenomas have expanded," says Richard W. Byrne, M.D., chair of Neurologic Surgery at Mayo Clinic in Florida. "Several factors should be considered when planning treatment. A major multidisciplinary center can outline the best approach for each individual."

Giant pituitary adenomas are defined as tumors that measure more than 4 centimeters in diameter. Although accounting for only 6% to 10% of all pituitary adenomas, giant tumors are likelier to cause neuro-ophthalmologic symptoms and hormonal deficits and to invade surrounding structures.

Detailed patient assessments are key to guiding treatment. Mayo Clinic's multidisciplinary team includes specialists in:

Endocrinology.
Neurologic Surgery.
Head and Neck Surgery.
Rhinology and Sinus Surgery.
Neuro-ophthalmology.
Neuroradiology.
Radiation Oncology.
Mayo Clinic's Pituitary-Gonad-Adrenal (PGA) Specialty Group.

"A thorough evaluation can identify patients who might be treated with medication and thus avoid surgery," Dr. Byrne says. "But it's important to note that giant pituitary adenomas treated only with medication might need prolonged, annual imaging to detect recurrences."

Surgery remains the main treatment option. The goal is to improve endocrinopathies and reduce the tumor's effects on surrounding structures while also preserving pituitary function.

As noted in a review published in the January 2024 issue of Operative Neurosurgery, endoscopic transnasal transsphenoidal surgery is increasingly applied to giant pituitary adenomas. "We prefer this approach even when giant pituitary adenomas extend into the third ventricle because it's associated with lower postoperative morbidity and a higher likelihood of preserving normal pituitary and visual function," Dr. Byrne says.

However, the surgical team's level of experience is critical. Mayo Clinic was among the first institutions to extensively research the endoscopic transnasal transsphenoidal approach.

"More-experienced surgeons have a better understanding of the practicalities of applying this procedure to giant pituitary adenomas," Dr. Byrne says.

Giant pituitary adenomas can displace critical arteries, impeding an endoscopic endonasal transsphenoidal approach. In those situations, Mayo Clinic surgeons tend to use a transcranial approach. "There are several techniques for these open procedures, each of which has advantages and disadvantages," Dr. Byrne says. Open surgery might be performed in combination with an endoscopic approach.

Gross total resection can be difficult to achieve, particularly when tumors extend laterally into the cavernous sinus. At Mayo Clinic, adjuvant treatment options include stereotactic radiosurgery, external beam radiation, intensity-modulated radiation therapy and proton beam therapy.

As one of the largest pituitary centers in the United States, Mayo Clinic has experience with even the most difficult adenomas. "The management of giant pituitary adenomas remains complex," Dr. Byrne says. "Experience with the range of modalities used in treatment, and with the associated endocrinopathies, is crucial for optimal patient care."