Extended field stereotactic radiosurgery for recurrent glioblastoma

Abstract

BACKGROUND: Stereotactic radiosurgery (SRS) is among the few therapeutic options for glioblastoma that recurs after standard radiation and chemotherapy, but its efficacy has been limited. METHODS: Since November 2007, the authors have modified the clinical target volume by adding a 0.5-to 1-cm margin to the gadolinium-enhanced area (extended field SRS), in contrast to conventional SRS using no margin to set the clinical target volume. A total of 35 recurred glioblastoma lesions in 9 patients were treated with conventional SRS between December 1990 and January 2007, and 14 lesions in 9 patients were treated with extended field SRS. RESULTS: The median follow-up periods were 7 months (range, 3-29 months) and 8 months (range, 6-27 months), respectively. The local control rate was 47% for conventional SRS and 93% for extended field SRS (P ¼ .0035), and the numbers of radiation necrosis observed in SRS-treated lesions were 2 and 4, respectively. The median overall survival from the diagnosis was 24 months (range, 14-57 months) for conventional SRS and 21 months (range, 15-51 months) for extended field SRS (statistically not significant). Seven patients treated with conventional SRS died during follow-up, 6 from progression of the SRS-treated tumor, whereas 7 patients treated with extended field SRS died during follow-up, 6 from remote intracerebral dissemination. CONCLUSIONS: Extended field SRS was superior to conventional SRS in the local control of small recurrent lesions of glioblastoma, although a further device to suppress remote dissemination may be necessary to increase survival. KEYWORDS: glioblastoma, glioma, gamma knife, stereotactic radiosurgery, radiation therapy, recurrence. INTRODUCTIONGlioblastoma is a highly malignant and aggressive tumor of the central nervous system that corresponds to grade IV of the World Health Organization histological classification. 1 The current standard treatment for glioblastoma is a maximal resection with functional preservation, followed by radiation and chemotherapy. When temozolomide is used for chemotherapy, the median survival is 14.6 months after initial presentation, 2 and ranges from 5 to 13 months after recurrence. 3,4 Because of the aggressive and invasive nature of the tumor, recurrence is seen in >90% of patients. 5 The most common pattern of recurrence is local regrowth 6 ; therefore, successful local control should lead to prolongation of patients' survival. Various local treatment strategies have been attempted, including repeated operations, conformal radiotherapy, brachytherapy, and local chemotherapy. 7 Although stereotactic radiosurgery (SRS) is an option as salvage treatment for recurrent glioblastoma in clinical settings, the role of SRS is still limited for glioma. SRS is useful in controlling relatively well-demarcated glioma such as ependymoma, pilocytic astrocytoma, and pleomorphic xanthoastrocytoma. [8][9][10][11][12][13] However, the majority of glioma is infiltrative to brain parenchyma and is difficult to target with SRS. A randomized controlle...

Efficacy and Limitations of Stereotactic Radiosurgery in the Treatment of Glioblastoma

“…Although extended field stereotactic radiosurgery achieved high local tumor control rate, no significant survival benefit was achieved, with overall survival of 9 months compared with 10.5 months after conventional stereotactic radiosurgery (p ＝ 0.83). 19) The overall survival after extended field stereotactic radiosurgery was also consistent with the results of only stereotactic radiosurgery for recurrent glioblastoma from other institutes at 5.3 to 13 months (median 10 months), 2,6,12,14,23,30,35,39) and apparently represent the limitation of survival benefit achieved by stereotactic radiosurgery for local treatment. In fact, six of seven patients who died after extended field stereotactic radiosurgery in our study, died of remote recurrence or dissemination (data not shown).…”

“…2) resulted in significant improvement of local control rate from 55% to 92%. 19) Local control might lead to improvement of performance status as achieved by surgical mass reduction, 1) but improvements in performance status associated with local control achieved by stereotactic radiosurgery remain unclear and further analyses are awaited. Although extended field stereotactic radiosurgery achieved high local tumor control rate, no significant survival benefit was achieved, with overall survival of 9 months compared with 10.5 months after conventional stereotactic radiosurgery (p ＝ 0.83).…”

“…21) However, the highly invasive nature of glioblastoma makes this disease uncontrollable by stereotactic radiosurgery, because this targeted irradiation spares viable cells surrounding the target. 19) Therefore, considerable advances are needed to effectively utilize stereotactic radiosurgery for the treatment of this challenging disease. Here we review outcomes of stereotactic radiosurgery and consider its role in the treatment of recurrent glioblastoma.…”

Case Series: Gamma Knife as Salvage Therapy for Recurrent Glioblastoma Multiforme

“…In the present study, RTOG-RPA Class was determined in 95% of patients with the greatest survival advantage appreciated by patients in Class IV: 20.2 months (Table 2) (Figure 4). In prior studies recently reviewed [38], median overall survival for all patients treated with salvage GKRS was from 16.7 to 33.2 months [15,16,18,[30][31][32][33][34][35]. It is also informative to analyze which patient characteristics predict longer survival following salvage therapy.…”

“…Stereotactic radiosurgery has also shown to provide a survival benefit for those in which repeat surgical resection is not indicated [29]. Multiple studies have offered evidence to support a survival benefit for select rGBM patients who receive GKRS salvage treatment [15,16,18,[30][31][32][33][34][35].…”