Analysis of radiosurgical results in patients with brain metastases according to the number of brain lesions: is stereotactic radiosurgery effective for multiple brain metastases?

Abstract

Object Whole-brain radiation therapy (WBRT), open resection, and stereotactic radiosurgery (SRS) are widely used for treatment of metastatic brain lesions, and many physicians recommend WBRT for multiple brain metastases. However, WBRT can be performed only once per patient, with rare exceptions. Some patients may require SRS for multiple metastatic brain lesions, particularly those patients harboring more than 10 lesions. In this paper, treatment results of SRS for brain metastasis were analyzed, and an attempt was made to determine whether SRS is effective, even in cases involving multiple metastatic brain lesions. Methods The authors evaluated the cases of 323 patients who underwent SRS between October 2005 and October 2008 for the treatment of metastatic brain lesions. Treatment was performed using the Gamma Knife model C or Perfexion. The patients were divided into 4 groups according to the number of lesions visible on MR images: Group 1, 1–5 lesions; Group 2, 6–10 lesions: Group 3, 11–15 lesions; and Group 4, > 15 lesions. Patient survival and progression-free survival times, taking into account both local and distant tumor recurrences, were analyzed. Results The patients consisted of 172 men and 151 women with a mean age at SRS of 59 years (range 30–89 years). The overall median survival time after SRS was 10 months (range 8.7–11.4 months). The median survival time of each group was as follows: Group 1, 10 months; Group 2, 10 months; Group 3, 13 months; and Group 4, 8 months. There was no statistical difference between survival times after SRS (log-rank test, p = 0.554), although the probability of development of new lesions in the brain was greater in Group 4 (p = 0.014). Local tumor control rates were not statistically different among the groups (log-rank test, p = 0.989); however, remote disease progression was more frequent in Group 4 (log-rank test, p = 0.014). Conclusions In this study, patients harboring more than 15 metastatic brain lesions were found to have faster development of new lesions in the brain. This may be due to the biological properties of the patients' primary lesions, for example, having a greater tendency to disseminate hematogenously, especially to the brain, or a higher probability of missed or invisible lesions (microscopic metastases) to treat on stereotactic MR images at the time of radiosurgery. However, the mean survival times after SRS were not statistically different between groups. According to the aforementioned results, SRS may be a good treatment option for local control of metastatic lesions and for improved survival in patients with multiple metastatic brain lesions, even those patients who harbor more than 15 metastatic brain lesions, who, after SRS, may have early and easily detectable new metastatic lesions.

Survival and Intracranial Control of Patients With 5 or More Brain Metastases Treated With Gamma Knife Stereotactic Radiosurgery

“…Together, these studies support our findings that KPS score, as opposed to the number of metastases, is more significantly associated with OS in patients undergoing SRS. Our finding of a trend towards worse intracranial diseasefree survival is consistent with an analysis of 323 patients with 1 to 5, 6 to 10, 11 to 15, and 16 to 20 brain metastases by Chang et al 18 Like ours, this study did not demonstrate differences in OS based on number of brain metastases. However, the patients with Z16 metastases in this study had a greater risk of intracranial recurrence (P = 0.014) and remote disease progression (P = 0.014).…”

Contrast-Enhanced 3-Dimensional SPACE Versus MP-RAGE for the Detection of Brain Metastases

“…Beyond achieving accuracy in the detection of metastatic lesions, as was done in the previous work, determining the exact number of metastatic lesions present on a given scan, as was done in our study, is critical because radiotherapy treatments are now being used for patients with more than 4 metastatic foci. 3,28 The present study is not without limitations. As noted in previous works, histologic confirmation of metastatic lesions is difficult because metastatic lesions are not typically resected in patients with multiple lesions.…”

“…1,2 However, patients with greater numbers of lesions are now routinely treated with stereotactic radiotherapy. 3 Because local control of metastases is more efficacious when lesion size is less than 10 mm in diameter, accurate detection of small brain metastases is critical.…”

Current strategies in the surgical management of cerebral metastases: an evidence-based review

“…36 Such a swing in the pendulum is supported by a growing body of retrospective data indicating that SRS is not only feasible but effective in treating even 20 or more brain metastases. 37,38 For instance, in a recent retrospective study analyzing the outcome of treating multiple brain metastases with SRS alone in 323 patients (mean age 59 years, KPS score P 70), of which 108 patients harboured more than five lesions and 33 more than 15, 38 the authors reported not only an overall favourable median survival of 10 months but more importantly the survival rate and local tumour control rate did not appear to depend on tumour multiplicity. These results, although limited by their retrospective nature, suggest that high tumour multiplicity alone should not be considered a contraindication for SRS.…”