Stereotactic Radiosurgery in the Management of Brain Metastasis

Michael L. Smith, M.D.; John Y. K. Lee, M.D.

Disclosures

Neurosurg Focus. 2007;22(3) 

In This Article

Craniotomy Compared with SRS

Comparative Efficacy

Resection of a single accessible brain metastasis in addition to WBRT has been the standard of care for single metastases in patients with other favorable prognostic factors. However, SRS is becoming more commonly available and a number of studies have demonstrated efficacy comparable with craniotomy, making the decision as to which is the optimal treatment more complex. Indeed, some authors have even suggested that SRS may supplant craniotomy as the new gold standard.[17]

One obvious disadvantage to SRS is the lack of histological confirmation of diagnosis. Among patients with known systemic cancer and a new brain lesion,[5] up to 11% may be harboring an alternative pathological entity such as a primary brain tumor, abscess, or even a hemorrhage.[13] Resection provides both the treatment and the opportunity for diagnosis. Therefore, resection–or at least biopsy sampling–should be considered for any patient without a clear diagnosis.

Several investigators have initiated randomized controlled trials to compare the efficacy of these two treatments. Patient accrual has been difficult, and the results are not yet available. In place of prospective data, one can try to glean data from the multiple retrospective studies that have been performed. There are three single-center retrospective analyses comparing SRS to craniotomy. Bindal et al.[5] studied 31 retrospectively matched patients treated with SRS and 62 patients treated with craniotomy. These authors found a median survival period of 7.5 months in the SRS group compared with 16.4 months in the craniotomy group (p = 0.0018). This study has been criticized because of an overt selection bias and differences in radiosurgical techniques and outcomes in comparison to other groups. Muacevic et al.[32] retrospectively reviewed 108 patients and compared a group of patients who underwent craniotomy and WBRT compared with those who underwent SRS alone. These authors found no significant difference in 1-year survival, 1-year local control, or morbidity and mortality rates. O'Neill et al.[36] studied 97 patients with single brain metastases, of whom 74 underwent craniotomy and 23 underwent SRS. Their rate of local failure for surgery was unusually high at 58%. None of the SRS patients had local failure. Regardless, they found no difference in 1-year survival.

Several authors have attempted to review the existing literature to determine the role of SRS compared with conventional craniotomy and resection. Sperduto[51] undertook a literature review and reached several conclusions: patients with a single accessible metastasis should undergo craniotomy; patients with one to three tumors and a KPS score greater than 70 should receive both SRS and WBRT; patients with more than three tumors and a KPS score less than 70 should undergo WBRT only. Boyd and colleagues[7] studied 21 reports of SRS for brain metastasis. Although they were unable to perform a definitive analysis due to data inhomogeneity, they found an average local control rate of 83% and median survival of 9.6 months. As noted in their report, this is comparable to the results of recent surgical series. Boyd and colleagues note the following characteristics that make metastasis amenable to SRS: lesion tendency toward spherical shape, gray-white junction location allowing the application of a large radiation dose with minimal toxicity, and frequent presentation at less than 3 cm diameter. In a literature review and commentary, Alexander and Loeffler[1] concluded that SRS is comparable to surgery and therefore surgery should be restricted to the minority of patients for whom the brain metastasis is immediately life threatening.

In summary, there is no confirmed clear advantage of one treatment over the other. The discomfort, risks, and costs of surgery must be justified to recommend this treatment to a patient. The two modalities have some complementary aspects. Stereotactic radiosurgery seems clearly preferable for small, multiple, and deep lesions, and in patients unlikely to tolerate general anesthesia well. Craniotomy should be recommended for single, large lesions causing herniation or a posterior fossa mass effect. For tumors that could reasonably be treated using either modality, patient and physician preference will play a large role and both modalities remain accepted practices.

Cost-effectiveness of SRS

Most studies demonstrate that SRS is a cost-effective treatment for patients with brain metastasis. Mehta et al.[29] undertook a cost-effectiveness analysis of patients with brain metastases, among whom 46 underwent resection, 135 received SRS, and 454 received WBRT alone. The authors found that surgery and SRS were similarly effective and superior to the use of WBRT alone. The net cost of surgery was 1.8-fold higher. The average cost per week of survival was $310 for WBRT, $524 for surgery and WBRT, and $270 for SRS and WBRT.

Rutigliano et al.[42] reviewed the literature on the economic efficiency of SRS or surgery with WBRT from 1974 to 1994 and had similar (although less dramatic) findings, stating the cost as $24,811/life year ($477/week) for SRS combined with WBRT compared with $32,149/life year ($618/week) for craniotomy. Thus, craniotomy is 1.3 times more expensive for the additional survival time offered com pared to 1.8 times more expensive as reported by Mehta et al.

In a Munich study, 127 patients with various diagnoses were treated with craniotomy or SRS. The SRS costs were determined by the global operating costs for the GKS center divided by the number of patients treated. Craniotomy costs included the costs of surgery, the intensive care unit, and inpatient and ancillary services. The costs of treating meningiomas, vestibular schwannomas, brain metastases, and arteriovenous malformations less than 3 cm in diameter averaged 15,242 euros for craniotomy and 7,920 euros for SRS.[56]

Compared with conventional craniotomy, SRS is a cost-effective treatment for brain metastasis. The decision to pursue craniotomy or SRS as a treatment in a particular patient should not be determined by economics. However, because cost, access, and resource management are increasingly important, these factors must be included in professional discussions of treatment algorithms.

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