Hypofractionated stereotactic radiotherapy for the treatment of brain metastases

Abstract

BACKGROUND: This retrospective review evaluated the efficacy and toxicity profiles of various dose fractionations using hypofractionated stereotactic radiotherapy (HSRT) in the treatment of brain metastases. METHODS: Between 2004 and 2007, 36 patients with 66 brain metastases were treated with HSRT. Nine of these subjects were excluded because of the absence of post‐treatment magnetic resonance imaging scans, resulting in 27 patients with a total of 52 lesions. Of these 52 lesions, 45 lesions were treated with whole‐brain radiotherapy plus a HSRT boost and 7 lesions were treated with HSRT as the primary treatment. The median prescribed dose was 25 grays (Gy) (range, 20 Gy‐36 Gy) with a median of 5 fractions (range, 4 fractions‐6 fractions) to a median 85% isodose line (range, 50%‐100%). The median follow‐up interval was 6.6 months (range, 0.9 months‐26.8 months). RESULTS: The median overall survival time was 10.8 months, and 66.7% of patients died of disease progression. After HSRT treatment of 52 brain lesions, 13 lesions demonstrated complete responses, 12 lesions demonstrated partial responses, 22 lesions demonstrated stable disease, and 5 lesions demonstrated progressive disease. Actuarial local tumor control rates at 6 months and 1 year were 93.9% and 68.2%, respectively. Maximum tumor dimension, concurrent chemotherapy, and a tumor volume <1 cc were found to be statistically significant factors for local tumor control. One patient had a grade 3 toxicity (according to National Cancer Institute Common Terminology Criteria for Adverse Events). CONCLUSIONS: HSRT provides a high level of tumor control with minimal toxicity comparable to single‐fraction stereotactic radiosurgery (SRS). The results of the current study warrant a prospective randomized study comparing single‐fraction SRS with HSRT in this patient population. Cancer 2009. © 2009 American Cancer Society.

Cyberknife hypofractionated stereotactic radiosurgery (HSRS) of resection cavity after excision of large cerebral metastasis: efficacy and safety of an 800 cGy × 3 daily fractions regimen

“…These studies suggest that local control rates of 68-91% may be achieved using regimens of 3-5 fractions, with cumulative doses ranging from 2000 to 3600 cGy [24,26,29,[48][49][50]. These results are largely consistent with those observed in our study.…”

Experiences on two different stereotactic radiosurgery modalities of Gamma Knife and Cyberknife in treating brain metastases

“…Fractionated administration of radiation dose potentially decreases toxicity to late-responding normal tissues compared to a single acute dose of radiation for a given level of tumor damage [23], and reoxygenation and redistribution of the cell cycle between fractions render hypoxic tumor cells and cells in a lessresponding cell cycle more radiosensitive [9,16]. As expected from this concept, recently published studies on fractionated SRS for large BMs have demonstrated high LTC rates ranging from 63 to 100 % at 1 year with acceptable risks of toxicity [4,5,8,10,11,13,14,21,22]. Along with these, in the present study, the LTC rate was 87.0 % at 1 year and the median OS was 16 months in patients with large BMs treated with fractionated CK, which also compares well with the outcomes of single-fraction SRS for small BMs [6,17,26].…”

“…Recently, the concept of fractionated SRS has been emerging and is reportedly effective and safe in treating BMs, especially large ones [4,5,8,10,11,13,14,21,22]. The Cyberknife (CK) (Accuray, Sunnyvale, CA, USA) features a more flexible fractionation delivery of SRS compared with GK, as it relies on the frameless, image-guided technology for tracking the target both in space and time.…”

Local control after fractionated stereotactic radiation therapy for brain metastases

“…At our institution, we use 25 Gy in 5 fractions most commonly, which is the most commonly used SRT fractionation regimen used in the United States according to a national survey of radiation oncologists who treat brain metastases with SRS/SRT [28]. The average reported local control rate after SRT is approximately 78 % (range 52-100 %) [15,[29][30][31][32][33][34][35][36][37][38][39][40], though many of the studies did not specifically isolate patients who did and did not receive WBRT. Two studies directly compared SRS with SRT, and there was no significant difference in local control or survival [31,32].…”