Pituitary Tumors and Gamma Knife Surgery - Clinical Experience with More Than Two Years of Follow-Up

Abstract

30 patients with pituitary tumors were treated in our unit and followed for 26–45 months. 14 patients had nonsecreting adenomas, 7 had acromegaly, 5 had prolactinomas, 3 had Cushing''s disease. One patient had a choristoma of the pituitary stalk. The patient with a choristoma, 7 patients with nonsecreting adenomas, 4 with acromegaly, 1 prolactinoma and 3 with Cushing’s disease had been operated by transsphenoidal microsurgery prior to Gamma Knife (GK) treatment. From this group, one patient with a nonsecreting adenoma and two with acromegaly had undergone fractional external radiotherapy after surgery. Stereotactic MRI localization had been used in all cases. All the tumors showed either a reduction in volume or cessation of growth; 85% of the patients with acromegaly showed normalization of growth hormone (GH) levels. Normalization of ACTH levels occurred in the 3 patients with Cushing’s disease. All the patients with prolactinomas showed reduction of prolactin levels but normalization did not occur. However, in 3 cases the bromocriptine could be withdrawn. Deterioration of vision was not observed. One patient suffered transient paresis of the third cranial nerve that improved with steroids. Panhypopituitarism appeared in one case of Cushing’s disease two years after the treatment. In the remaining cases there were no changes in their previous physiological pituitary function. We conclude that GK radiosurgery in pituitary tumors is an effective alternative to transsphenoidal microsurgery when compression of surrounding structures does not exist, and it can efficiently replace conventional irradiation.

Stereotactic Radiosurgery with the CyberKnife for Pituitary Adenomas

“…Therefore, additional therapy after operation is often necessary. For such cases, conventional external radiation has been known to be effective, but it takes several years to achieve endocrinological remission and also carries a significant risk for panhypopituitarism or visual disturbances 20,25,26) . Radiosurgery can be a first choice of treatment, achieving both growth control and hormonal remission with minimum neurological complications, which is equivalent to conventional radiation therapy but with much less risk of radiation injury to the surrounding structures.…”

Radiation therapy in the treatment of pituitary tumors

“…Witt et al 51 reviewed 20 different radiosurgery studies published between 1997 and 2002 and found that tumor control ranged from 68 to 100% (but most studies showed Ͼ 90% growth control). He also found endocrine improvement in 0 16,29,53,54 to 67%, 35 depending on the study. The endocrine cure in the different studies ranged from 0 16,36 to 96%.…”

“…In a review of 17 different radiosurgery studies published from 1997 to 2002, Witt 50 found that endocrine improvement was achieved with radiosurgery in 29 43 to 100% 29,36 of cases. Tumor control is achieved in most studies in Ͼ 90% of cases, 29,36,43,54 with the exception of 1 study in which only a 68% growth control rate was reported. 16 Cure after radiosurgery was difficult to assess because persistent mild hypersecretion of prolactin may have developed in many patients due to the radiation-induced destruction of the stalk, and therefore to the inhibitory effect of dopaminergic neurons.…”

Tratamento medicamentoso dos tumores hipofisários. Parte I: prolactinomas e adenomas secretores de GH

“…Os dados com a radiocirurgia gamma-knife -que permite liberar, com acurácia milimétrica e de uma só vez, dosess maiores de radiação para o núcleo do tumor, com menor agressão sobre o hipotálamo, quiasma óptico e cérebro -são ainda limitados (69). Em três estudos, totalizando 16 pacientes, não houve normalização dos níveis de PRL, mas redução dos mesmos aconteceu na maioria dos casos (69)(70)(71). A radioterapia deve ser reservada para prolactinomas (sobretudo, os invasivos) sem resposta adequada às outras formas de tratamento (16).…”