Stereotactic radiosurgery (SRS) for multiple metastatic brain tumors: effects of the number of target tumors on exposure dose in normal brain tissues.
ABSTRACT This study was carried out to clarify the practical limit of the number of stereotactic radiosurgery (SRS)-targeted tumors based on the irradiation dose of normal brain tissues.
Twenty-five patients with multiple brain metastases who received SRS from October 1998 to May 2002 were enrolled in the study. In each patient, the treatment options were thoroughly studied before deciding upon a course of treatment. The number of irradiated targets was increased one by one until all of the targets were included in a treatment plan. Given a surface dose of 25 Gy, we calculated the dose volume histogram (DVH) for the entire brain in each treatment plan and compared it with those of other treatment plans. Ultimately, only 5 of the 25 patients received irradiation for all of their tumors; the others received selective irradiation targeting only those tumors that were causing symptoms.
When the number of targets increased, the DVH curve shifted to the right. The volume of the brain irradiated at a dose of 5 Gy or higher was 25.7% or less for 4 or fewer targets, 45.7% for 5-6 targets, 81.0% for 7-8 targets and 100% for 9-11 targets. When the number of the targets exceeded 8, more than 50% of the entire brain was irradiated at levels of at least 8.7 Gy. The dose distribution became very complex as the number of targets increased. Although the survival time of the group in which tumors were selectively targeted was longer than that in the group in which all tumors were irradiated, the difference between the two groups was not statistically significant ( P = 0.2537).
In SRS for multiple brain metastases, risks of both acute and late sequelae may increase because the exposure dose to normal brain tissues increases with increased numbers of target tumors. Dose distribution becomes more complex according to the increase in the number of targets. Based on our DVH curves, we conclude that the exposure dose to normal brain tissues is acceptable when the number of targets is less than 7. Importantly, our study also reveals that it may not be necessary or desirable to irradiate all metastatic tumors.
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ABSTRACT: Initial staging workup of non-small cell lung cancer (NSCLC) patients has led to increased identification of incidental brain metastases in patients who otherwise have minimal or no neurologic symptoms. We present our experience treating these metastases with stereotactic radiosurgery (SRS) alone and compare outcomes to those of patients with brain metastases treated with other strategies. We queried our neuro-oncology and radiation oncology databases for patients with incidentally-identified NSCLC brain metastases treated with upfront SRS alone between 1997 and 2006. We performed a retrospective analysis to evaluate outcomes in these patients. We found 26 patients with incidentally-identified NSCLC brain metastases (KPS 90-100) treated with SRS alone within 60 days of diagnosis of the metastases. These patients underwent SRS at a median 15 days from diagnosis to an average of 1.6 lesions (range: 1-7), with a mean lesion volume of 1.86 cm(3). The median prescription was 24 Gy delivered to the median 53% isodose line. The median survival for these patients was 8.2 months (mean 12.3 months) from diagnosis of brain metastases. Local CNS progression occurred in 2 patients (7.7%, mean 229.7 days). Survival was not statistically different from similar patients treated with whole brain radiotherapy (WBRT) (P = 0.98), WBRT + Surgery (P = 0.07) or WBRT + SRS (P = 0.62). Patients with incidentally-identified NSCLC brain metastases treated with SRS alone may achieve a survival rate comparable to patients managed with other standard therapeutic modalities. Our findings suggest that SRS alone may be a viable therapeutic option for patients with incidentally-discovered NSCLC brain metastases.Journal of Neuro-Oncology 03/2011; 104(3):817-24. · 3.12 Impact Factor
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ABSTRACT: To our knowledge, there are no published reports on the effectiveness of radiosurgery in the management of brain metastases from testicular nonseminomatous germ cell tumor. The authors evaluate the results of gamma knife (GK) treatment in three patients with these unusual intracranial lesions. Between April 1995 and July 2001, three patients with brain metastasis from testicular nonseminomatous germ cell tumor underwent adjuvant radiosurgery at our department. The primary tumor had been surgically removed in all cases. At diagnosis, one patient was stage IB and two were stage III poor risk. Chemotherapy and whole brain radiotherapy were administered before radiosurgery in all cases. Pre-GK radiotherapy was administered with a daily fraction dosage of 1.8-2.0 Gy. The indications for radiosurgery were tumor volume <20 cm3, microsurgery too risky, refusal of surgery. All the lesions were located in eloquent brain areas. Post-GK high-dose chemotherapy with autologous peripheral-blood stem-cell rescue was administered in two cases due to systemic recurrence of the disease. All patients are still alive with a median and mean follow-up period after radiosurgery of 63 and 68.3 mo, respectively. They had no neurological deficits at the latest examination. Neuroradiological follow-up invariably showed tumor growth control (complete response in two cases and partial response in one) with typically delayed post-radiosurgical imaging changes (transient in two cases and long-lasting in one). In conclusion, GK seems to be highly effective and safe in brain metastases from testicular nonseminomatous germ cell tumor. In cases with diffuse metastatic brain involvement, the whole brain radiotherapy preceding radiosurgery should be delivered with 1.8 Gy daily fraction to prevent the risk of long-lasting post-radiosurgical imaging changes.Medical Oncology 02/2005; 22(1):45-56. · 2.15 Impact Factor
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ABSTRACT: The aim of this study was to analyze factors influencing survival time and patterns of distant recurrences after Gamma Knife surgery (GKS) for metastases to the brain. Information was available for 1855 of 1921 patients who underwent GKS for single or multiple cerebral metastases at 4 different institutions during different time periods between 1975 and 2007. The total number of Gamma Knife treatments administered was 2448, an average of 1.32 treatments per patient. The median survival time was analyzed, related to patient and treatment parameters, and compared with published data following conventional fractionated whole-brain irradiation. Twenty-five patients survived for longer than 10 years after GKS, and 23 are still alive. Age and primary tumor control were strongly related to survival time. Patients with single metastases had a longer survival than those with multiple metastases, but there was no difference in survival between patients with single and multiple metastases who had controlled primary disease. There were no significant differences in median survival time between patients with 2, 3-4, 5-8, or >8 metastases. The 5-year survival rate was 6% for the whole patient population, and 9% for patients with controlled primary disease. New hematogenous spread was a more significant problem than micrometastases in patients with longer survival. Patient age and primary tumor control are more important factors in predicting median survival time than number of metastases to the brain. Long-term survivors are more common than previously assumed.Journal of Neurosurgery 02/2009; 111(3):449-57. · 3.15 Impact Factor