Role of gamma knife radiosurgery in the management of functioning pituitary adenomas

Abstract

Historically, the treatment armamentarium for secretory pituitary adenomas included neurosurgery, medical management, fractionated radiotherapy, and, recently, gamma knife surgery (GKS). The objective of this study was to evaluate the efficacy, safety, and role of GKS in the treatment of secretory pituitary adenomas as regards hormonal and adenoma size control. Between January 2010 and January 2014, a prospective analysis of 40 consecutive patients who underwent GKS for secretory pituitary adenomas at the International Medical Center, Cairo, Egypt, was carried out. Eight patients had adrenocorticotropic hormone-secreting adenoma, 16 patients had prolactin-secreting adenoma, and 16 had growth hormone-secreting adenoma. In 19 patients, GKS was the secondary treatment to a prior surgery with failure of hormonal control along with medical treatment. In the remaining 21 patients, the secretory pituitary adenomas were not controlled with medical treatment alone. The follow-up period ranged between 12 and 60 months. Hormonal control was achieved with either normalization or a marked decline in abnormal hormone level of more 50%. Radiological tumor size control was carried out with either tumor size stabilization or reduction. Among the 40 patients, 21 had microadenoma of 1 cm 3 volume or less. Overall, 24 patients (60%) had hormonal control and 38 patients (95%) had tumor size control after GKS. There was a direct correlation between tumor size, prescription radiation dose, and hormonal and size control after GKS. Twenty out of the treated 21 microadenoma cases showed both hormonal and size control. In conclusion, GKS is a safe and effective treatment method for secretory pituitary adenomas that have failed to respond to medical treatment alone or have postsurgical residual tumor, or recurrence, especially microadenomas.