Stereotactic Radiosurgery/Radiotherapy for Pituitary Adenomas: A Review of Recent Literature

Abstract

The recent clinical results are reviewed of stereotactic radiosurgery/radiotherapy for the treatment of pituitary adenomas. The outcomes of pituitary adenomas treated by stereotactic radiosurgery/radiotherapy with gamma knife, CyberKnife, or linear accelerator (LINAC) radiosurgery were evaluated from articles published after 2004. Each study was evaluated for the number of patients, radiosurgical parameter (marginal dose), length of follow up, tumor growth control, rate of hormonal normalization in secretary adenomas, and adverse events. After gamma knife radiosurgery, the tumor reduction rates varied from 42.3% to 89% in non-secreting adenomas. However, the tumor control rates in non-secreting adenomas were more than 90% in most studies. In growth hormone-secreting adenomas, the rates of insulin-like growth factor-1 normalization ranged from 36.9% to 82%. In adrenocorticotropin-secreting adenomas, the rates for 24-hour urine free cortisol normalization ranged from 27.9% to 54%. In prolactin-secreting adenomas, the prolactin normalization ranged from 17.4% to 50%. New hormonal deficits ranged from 0% to 34%. New visual deficits were relatively low. The number of patients treated with CyberKnife and LINAC radiosurgery/radiotherapy was small and follow-up periods were relatively short compared to those with gamma knife treatment, but the clinical outcomes after these therapies were similar to those after gamma knife therapy. Image-guided stereotactic radiosurgery/radiotherapy with the gamma knife, CyberKnife, or LINAC system is effective and safe against pituitary adenomas. Careful long-term follow up of the patients is necessary because of longterm anti-tumor effects and delayed adverse events.

LINAC-radiosurgery for nonsecreting pituitary adenomas

“…4. The first reports of CyberKnife treatment of pituitary adenomas are available [7,19,22]. Despite the few cases with short follow-up, it can be recognized that optimal radiation dose and application mode have to be elaborated.…”

Development of a modified head and neck quality assurance phantom for use in stereotactic radiosurgery trials

“…It has been shown that pituitary adenomas, such as acromegaly, can be safely and effectively treated with stereotactic radiosurgery (SRS) (1,2) . Frequently used radiosurgery systems for treating such brain lesions include Gamma Knife, (1,3–5) CyberKnife, (1,6,7) and linear accelerator (linac)‐based treatments (1,8,9) . Because each system involves higher‐than‐normal doses per fraction and steep dose gradients, (2,8) there is an increased importance to accurately delivering the treatment to the patient (2) .…”

Dosimetric impact of multileaf collimator leaf width according to sophisticated grade of technique in the IMRT and VMAT planning for pituitary adenoma lesion

“…Several studies have reported that pa prescribed dose of 20-29 Gy to a pituitary adenoma resulted in an 82-100% tumor control rate, and therefore, in this planning study, we used a prescribed dose of 25 Gy to the target volume [14–18]. …”