Gamma knife radiosurgery for cranial neurocytomas

Abstract

Gamma-knife surgery may be an effective alternative for treatment of central neurocytomas owing to its relative safety compared with conventional radiotherapy. In this paper we present results of gamma-knife treatment (GKS) of residual or recurrent neurocytomas. Twenty-two patients (14 female, 8 male) with recurrent or residual neurocytomas who underwent GKS were included. Diagnosis was based on histological findings. The proliferative potential of the tumors was examined by immunostaining with MIB-1 antibody, which is specific for detection of Ki-67 antigen. Tumor volume was determined by using post-gadolinium magnetic resonance images. After GKS treatment, MR imaging was scheduled at three-month intervals in the first year, at six months intervals in the second year, and yearly thereafter. Histopathological diagnoses were: 18 cases of central neurocytomas, two liponeurocytomas, one cerebral neurocytoma and one cerebellar neurocytoma. The MIB1 labeling index (LI) varied from 0 to 5.7%. Marked reduction in tumor volume was seen in 15 patients. In six patients, the tumor volume remained unchanged, and progression was observed for one patient. No complications because of GKS were noted. Shrinking effect on tumor volume increased with increasing duration of follow-up. On the other hand, high MIB labeling index did not seem to have an effect on tumor response to GKS treatment. Findings of this study suggest that GKS is an effective and safe treatment alternative for residual or recurrent neurocytomas. However, its effectiveness should be confirmed with larger studies.

Cerebellar liponeurocytoma: A case report and review of the literature

“…Although there is no such comparison for the surgery and radiation, there is a trend showing that post-operative radiotherapy benefits the outcome, as suggested by Jackson et al (10). Genc et al reported 2 cases of cerebellar liponeurocytoma with post-surgery γ-knife therapy, and observed that the tumors diminished in size after a follow-up time of 12 and 53 months, respectively (11). However, certain studies believe that since the recurrence of the tumor occurs in the long term, adjuvant radiation is too aggressive following the initial gross total resection (2)(3)(4)9).…”

“…Considering that there is no evidence to support the use of adjuvant radiation in the prevention of recurrence and due to the side-effects of radiation, the majority of studies in the literature recommended a gross total resection, with a focus on quality of life, and a long-term follow-up plan (7)(8)(9). When recurrence was observed, repeat surgery and adjuvant radiation was recommended, as the pathology of the recurrence was always more aggressive than the primary tumor (10)(11)(12).…”

Gamma knife radiosurgery of recurrent atypical neurocytoma

“…Due to the steep dose gradient at the edge of the target volume, the included margin of normal brain tissue can be minimized. This may result in a reduction of treatment-related early or late toxicity [1,9,21,23,27]. In view of the excellent prognosis of NC patients, with reported long-term survival rates of 93-100% [23], a highly conformal radiation technique is required to reduce the risk of late toxicities such as leukoencepahlopathy, cognitive dysfunction, white matter necrosis, intracerebral vasculopathy, or even radiation-induced malignancies [6,15,19,23].…”

“…1 [1,3,4,7,9,10,13,14,17,21,23,26,28,31]. Most of the reports are small retrospective case series including <10 patients [1,3,4,7,17,28], four papers are single case reports [10,13,21,31], and only three series provided results in >10 patients [9,14,23]. Kim et al [14] presented a series of 13 patients who underwent GKRS as primary treatment approach (n=6) as well as for residual or recurrent disease (n=7).…”

“…After a median follow-up of 61 months (range 6-96 months), LC was reported in 11 patients (84.6%). In a recent study, Genc et al [9] analyzed 22 patients retrospectively and reported a marked decrease of tumor volume in 15 patients, stable disease in 6, and local progression in 1 case after a median follow-up of 24 months (range 6-110 months). The mean tumor volume in the so far published cases varied from 2.7 to 14.8 cm 3 , and the mean marginal doses were in the range of 9.6-20.0 Gy.…”