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: 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. DOI:10.1385/MO:22:1:045 · 2.06 Impact Factor
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ABSTRACT: Brain metastases continue to be a major and growing challenge in oncology, but recent advances in surgery, radiosurgery, and chemotherapy have broadened the number of treatment options. Current approaches to the management of brain metastases focus on individualizing patient care based on factors including the Karnofsky Performance Status, the tumor histology, the number of metastases, and the status of the systemic disease. A number of treatment approaches have been shown to be effective for brain metastases, including surgery; radiosurgery; whole-brain radiotherapy; and, more recently, chemotherapy. The use of adjuvant whole-brain radiotherapy with local therapies, such as surgery or radiosurgery, along with newer chemotherapy options, such as targeted biological agents, temozolomide, and implantable 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) Gliadel wafers, are at the forefront of recent advances in the treatment of patients with brain metastases that may provide longer survival and improved quality of life. Although there is no current standard treatment, some general guidelines are recommended for single metastases, oligometastases (two to three brain metastases), and multiple (four or more) brain metastases, and for new or recurrent disease. With advances in systemic therapy for cancer, the treatment of brain metastases is becoming an increasingly important determinant of the length of survival and quality of life for cancer patients.Neurosurgery 12/2005; 57(5 Suppl):S66-77; discusssion S1-4. DOI:10.1227/01.NEU.0000182739.84734.6E · 3.03 Impact Factor
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ABSTRACT: Radiosurgery offers patients with brain metastases an effective and minimally invasive treatment modality. Radiosurgery provides local tumor control and prolongs survival in select patients with brain metastases. This review will discuss numerous aspects of radiosurgery, including the various delivery techniques and radiobiology. Treatment recommendations will be outlined in view of the available clinical data. Although surgery or radiosurgery with whole-brain radiotherapy remains an important option for patients with a solitary brain metastasis, radiosurgery with or without whole-brain radiotherapy should be considered in patients with a limited number of small tumors and a good prognosis.Neurosurgery 12/2005; 57(5 Suppl):S45-53; discusssion S1-4. DOI:10.1227/01.NEU.0000182741.82422.14 · 3.03 Impact Factor