International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationsInitial clinical results of linac-based stereotactic radiosurgery and stereotactic radiotherapy for pituitary adenomas
Introduction
Pituitary adenomas comprise about 10% of brain tumors (1). Although the majority of these tumors are histologically benign, they have the potential to severely deteriorate the patient’s quality of life by causing a visual disturbance and/or various clinical syndromes if they produce excessive pituitary hormones.
Medical management using bromocriptine or other drugs may provide temporary control of prolactinomas; however, this may have distressing side effects, and tumor relapse is uniformly seen after discontinuation of the drug treatment (2). In addition, this treatment is generally not effective for non-secreting adenomas, Cushing’s disease, or acromegaly (3).
For pituitary tumors larger than 1 cm in diameter, surgical removal is the treatment of choice (4). Almost all pituitary adenomas can be treated successfully by trans-sphenoidal surgery, which is generally less invasive and safer than craniotomy.
External beam radiation therapy (EBRT) has been used alone and as an adjunct to initial surgical debulking. In combination with surgery, conventional EBRT has been reported to provide 85% or higher tumor control over 10 years 5, 6, 7, 8, 9.
Stereotactic radiosurgery (SRS) has an advantage over conventional EBRT in that it can minimize the dose of radiation to the adjacent normal tissue by sharply focusing the dose distribution. In addition, stereotactic radiotherapy (SRT) is expected to have a further radiobiological advantage by fractionating the prescribed dose (10).
We herein report our initial clinical experience with SRS and SRT for pituitary adenomas, and we discuss the usefulness of these techniques in the treatment of pituitary adenomas.
Section snippets
Patient characteristics
Generally, radiation therapy for pituitary adenomas has been indicated for the following conditions: (a) Surgery is medically contraindicated or the patient refuses to undergo surgery; (b) the patient has a demonstrable re-growth of a non-functioning tumor after surgery; and (c) the patient has a residual functioning tumor which is likely to cause a persistent endocrine abnormality after surgery.
With these indications, 57 patients underwent radiation therapy for pituitary adenomas at the
Survival
The median follow-up for the whole patient population was 36 months (47 months for SRS and 34 months for SRT). There were 2 deaths among the 48 patients within the follow-up period. A 78-year-old male died of a massive cerebral hemorrhage in the frontal region 15 months after SRS, and an 81-year-old male died 33 months after SRS. The cause of his death was not documented. Consequently, the overall 3-year survival rate was 93.5% (84.4% for SRS and 100% for SRT) (Fig. 1 ). The 3-year survival
Discussion
Pituitary adenomas are best managed by a carefully considered combination of surgery, medical therapy, or radiation therapy. Radiation therapy in conjunction with initial surgical debulking has been repeatedly reported to further reduce the excessive hormonal secretion and lower the probability of recurrence 14, 15, 16, 17. The reported tumor control rates with postoperative EBRT range from 85% to 90% at 10 years 5, 6, 7, 8, 9. Although the 3-year tumor control rate of 91% in the present series
References (36)
- et al.
Radiotherapy of pituitary tumors
Endocrinol Metab Clin North Am
(1987) - et al.
External irradiation of macroinvasive pituitary adenomas with telecobalt: A retrospective study with long-term follow-up in patients irradiated with doses mostly of between 40–45 Gy
Int J Radiat Oncol Biol Phys
(1995) - et al.
External radiotherapy of pituitary adenomas
Int J Radiat Oncol Biol Phys
(1995) - et al.
Radiation therapy for pituitary adenoma: Treatment outcome and prognostic factors
Int J Radiat Oncol Biol Phys
(1994) - et al.
Long-term follow-up of radiotherapy for pituitary adenoma: The absence of late recurrence after greater than or equal to 4500 cGy
Int J Radiat Oncol Biol Phys
(1991) - et al.
Treatment planning for stereotactic radiosurgery of intra-cranial lesions
Int J Radiat Oncol Biol Phys
(1991) - et al.
Stereotactic radiotherapy for pediatric and adult brain tumors: Preliminary report
Int J Radiat Oncol Biol Phys
(1994) - et al.
Image fusion for stereotactic radiotherapy and radiosurgery treatment planning
Int J Radiat Oncol Biol Phys
(1994) - et al.
Nonpuerperal galactorrhea and hyperprolactinemia. Clinical findings endocrine features and therapeutic responses in 56 cases
Am J Med
(1977) - et al.
Gamma knife surgery for Cushing’s disease
Surg Neurol
(1995)
Dynamic field shaping for stereotactic radiosurgery: A modeling study
Int J Radiat Oncol Biol Phys
Variables associated with the development of complications from radiosurgery of intracranial tumors
Int J Radiat Oncol Biol Phys
Brain
Management of nonfunctioning pituitary adenomas
Acta Endocrinol
Nonsecretory pituitary adenomas
Radiation therapy in the treatment of pituitary adenomas
Am J Clin Oncol
Stereotactic radiotherapy: A technique for dose optimization and escalation for intracranial tumors
Acta Neurochir
The treatment of pituitary chromophobe adenomas
Radiology
Cited by (0)
- 1
Present address: Department of Radiology, Faculty of Medicine, Kyoto University, Kyoto 606-01, Japan.