Stereotactic radiosurgery for non-vestibular cranial nerve schwanommas.

Non-vestibular cranial nerve schwannomas (NVCNS) are rare lesions, representing <10 % of cranial nerve schwannomas. The optimal treatment for NVCNS is often derived from vestibular schwannomas experience. Surgical resection has been referred to as the first line treatment for those benign tumors, but significant complication rates are reported.

CyberKnife Stereotactic Radiosurgery for Atypical and Malignant Meningiomas.

Objective: Recurrent World Health Organization (WHO) grade II and III meningiomas have traditionally been treated by surgery alone, but early literature suggests that adjuvant stereotactic radiosurgery may greatly improve outcomes. We present the long-term tumor control and safety of a hypofractionated stereotactic radiosurgery regimen.

Methods: Prospectively collected data of 44 WHO grade II and 9 WHO grade III meningiomas treated by CyberKnife for adjuvant or salvage therapy were reviewed.

Dose-Response Modeling of the Visual Pathway Tolerance to Single-Fraction and Hypofractionated Stereotactic Radiosurgery.

Patients with tumors adjacent to the optic nerves and chiasm are frequently not candidates for single-fraction stereotactic radiosurgery (SRS) due to concern for radiation-induced optic neuropathy. However, these patients have been successfully treated with hypofractionated SRS over 2-5 days, though dose constraints have not yet been well defined. We reviewed the literature on optic tolerance to radiation and constructed a dose-response model for visual pathway tolerance to SRS delivered in 1-5 fractions.

The Parotid Gland is an Underrecognized Organ at Risk for Craniospinal Irradiation.

Purpose: Current craniospinal irradiation (CSI) protocols do not include the parotid gland as an organ at risk, potentially leading to late effects of xerostomia and secondary parotid malignancies. We analyzed the effect of CSI treatment parameters on parotid dose.

Materials And Methods: We retrospectively reviewed 50 consecutive patients treated with CSI to an intracranial dose >26 Gy.

Risk of leptomeningeal disease in patients treated with stereotactic radiosurgery targeting the postoperative resection cavity for brain metastases.

Purpose: We sought to determine the risk of leptomeningeal disease (LMD) in patients treated with stereotactic radiosurgery (SRS) targeting the postsurgical resection cavity of a brain metastasis, deferring whole-brain radiation therapy (WBRT) in all patients.

Methods And Materials: We retrospectively reviewed 175 brain metastasis resection cavities in 165 patients treated from 1998 to 2011 with postoperative SRS. The cumulative incidence rates, with death as a competing risk, of LMD, local failure (LF), and distant brain parenchymal failure (DF) were estimated.

Cavity volume dynamics after resection of brain metastases and timing of postresection cavity stereotactic radiosurgery.

Background: An alternative treatment option to whole-brain irradiation after surgical resection of brain metastases is resection cavity stereotactic radiosurgery (SRS).

Objective: To review the dynamics of cavity volume change after surgical resection with the goal of determining the optimal timing for cavity SRS.

Methods: Preresection tumor, postresection/pre-SRS cavity, and post-SRS cavity volumes were measured for 68 cavities in 63 patients treated with surgery and postresection cavity SRS.

Stereotactic radiosurgery of the postoperative resection cavity for brain metastases: prospective evaluation of target margin on tumor control.

Purpose: Given the neurocognitive toxicity associated with whole-brain irradiation (WBRT), approaches to defer or avoid WBRT after surgical resection of brain metastases are desirable. Our initial experience with stereotactic radiosurgery (SRS) targeting the resection cavity showed promising results. We examined the outcomes of postoperative resection cavity SRS to determine the effect of adding a 2-mm margin around the resection cavity on local failure (LF) and toxicity.

What is the optimal treatment of large brain metastases? An argument for a multidisciplinary approach.

Purpose: Single-modality treatment of large brain metastases (>2 cm) with whole-brain irradiation, stereotactic radiosurgery (SRS) alone, or surgery alone is not effective, with local failure (LF) rates of 50% to 90%. Our goal was to improve local control (LC) by using multimodality therapy of surgery and adjuvant SRS targeting the resection cavity.

Patients And Methods: We retrospectively evaluated 97 patients with brain metastases >2 cm in diameter treated with surgery and cavity SRS.

A planned neck dissection is not necessary in all patients with N2-3 head-and-neck cancer after sequential chemoradiotherapy.

Purpose: To assess the role of a planned neck dissection (PND) after sequential chemoradiotherapy for patients with head-and-neck cancer with N2-N3 nodal disease.

Methods And Materials: We reviewed 90 patients with N2-N3 head-and-neck squamous cell carcinoma treated between 1991 and 2001 on two sequential chemoradiotherapy protocols. All patients received induction and concurrent chemotherapy with cisplatin and 5-fluorocuracil, with or without tirapazamine.

Stereotactic radiosurgery yields long-term control for benign intradural, extramedullary spinal tumors.

Background: The role of stereotactic radiosurgery in the treatment of benign intracranial lesions is well established. Although a growing body of evidence supports its role in the treatment of malignant spinal lesions, a much less extensive dataset exists for treatment of benign spinal tumors.

Objective: To examine the safety and efficacy of stereotactic radiosurgery for treatment of benign, intradural extramedullary spinal tumors.

Multisession stereotactic radiosurgery for vestibular schwannomas: single-institution experience with 383 cases.

Background: Single-session stereotactic radiosurgery (SRS) treatment of vestibular schwannomas results in excellent tumor control. It is not known whether functional outcomes can be improved by fractionating the treatment over multiple sessions.

Objective: To examine tumor control and complication rates after multisession SRS.

Normal tissue complication probability estimation by the Lyman-Kutcher-Burman method does not accurately predict spinal cord tolerance to stereotactic radiosurgery.

Purpose: To determine whether normal tissue complication probability (NTCP) analyses of the human spinal cord by use of the Lyman-Kutcher-Burman (LKB) model, supplemented by linear-quadratic modeling to account for the effect of fractionation, predict the risk of myelopathy from stereotactic radiosurgery (SRS).

Methods And Materials: From November 2001 to July 2008, 24 spinal hemangioblastomas in 17 patients were treated with SRS. Of the tumors, 17 received 1 fraction with a median dose of 20 Gy (range, 18-30 Gy) and 7 received 20 to 25 Gy in 2 or 3 sessions, with cord maximum doses of 22.

Tolerance of the spinal cord to stereotactic radiosurgery: insights from hemangioblastomas.

Purpose: To evaluate spinal cord dose-volume effects, we present a retrospective review of stereotactic radiosurgery (SRS) treatments for spinal cord hemangioblastomas.

Methods And Materials: From November 2001 to July 2008, 27 spinal hemangioblastomas were treated in 19 patients with SRS. Seventeen tumors received a single fraction with a median dose of 20 Gy (range, 18-30 Gy).

Stereotactic radiosurgery of cranial nonvestibular schwannomas: results of single- and multisession radiosurgery.

Background: Surgical resection of nonvestibular cranial schwannomas carries a considerable risk of postoperative complications. Stereotactic radiosurgery (SRS) offers a non-invasive treatment alternative. The efficacy and safety of multi-session SRS of nonvestibular cranial schwannomas has not been well studied.

Cyberknife stereotactic radiosurgery for treatment of atypical (WHO grade II) cranial meningiomas.

Background: The optimal management of subtotally resected atypical meningiomas is unknown.

Objective: To perform a retrospective review of patients with residual or recurrent atypical meningiomas treated with stereotactic radiosurgery (SRS).

Methods: Twenty-five patients were treated, either immediately after surgery (n = 15) or at the time of radiographic progression or treatment failure (n = 10).

Stereotactic radiosurgery for treatment of spinal metastases recurring in close proximity to previously irradiated spinal cord.

Purpose: As the spinal cord tolerance often precludes reirradiation with conventional techniques, local recurrence within a previously irradiated field presents a treatment challenge.

Methods And Materials: We retrospectively reviewed 51 lesions in 42 patients treated from 2002 to 2008 whose spinal metastases recurred in a previous radiation field (median previous spinal cord dose of 40 Gy) and were subsequently treated with stereotactic radiosurgery (SRS).

Results: SRS was delivered to a median marginal dose of 20 Gy (range, 10-30 Gy) in 1-5 fractions (median, 2), targeting a median tumor volume of 10.

Multisession cyberknife stereotactic radiosurgery of large, benign cranial base tumors: preliminary study.

Objective: Although radiosurgery plays an important role in managing benign cranial base lesions, the potential for increased toxicity with single-session treatment of large tumors is a concern. In this retrospective study, we report the intermediate-term rate of local control, morbidity, and clinical outcomes of patients with large cranial base tumors treated with multisession stereotactic radiosurgery with the CyberKnife (Accuray, Inc., Sunnyvale, CA).

Stereotactic radiosurgical treatment of cranial and spinal hemangioblastomas.

Objective: Stereotactic radiosurgery has been used for nearly 2 decades to treat hemangioblastomas, particularly those that are in surgically inaccessible locations or that are multiple, as is common in von Hippel-Lindau disease. There is a paucity of long-term published radiosurgical treatment outcomes, particularly for spinal lesions, in a large patient population. The purpose of this study was to provide a long-term retrospective evaluation of radiosurgical hemangioblastoma treatment effectiveness, with a special emphasis on the relatively recent use of frameless, image-guided radiosurgery in the treatment of spinal lesions.

Molecular imaging of hypoxia-inducible factor 1 alpha and von Hippel-Lindau interaction in mice.

Tumor hypoxia plays a crucial role in tumorigenesis. Under hypoxia, hypoxia-inducible factor 1 alpha (HIF-1 alpha) regulates activation of genes promoting malignant progression. Under normoxia, HIF-1 alpha is hydroxylated on prolines 402 and 564 and is targeted for ubiquitin-mediated degradation by interacting with the von Hippel-Lindau protein complex (pVHL).

Stereotactic radiosurgery of the postoperative resection cavity for brain metastases.

Purpose: The purpose of this study was to analyze results of adjuvant stereotactic radiosurgery (SRS) targeted at resection cavities of brain metastases without whole-brain irradiation (WBI).

Methods And Materials: Patients who underwent SRS to the tumor bed, deferring WBI after resection of a brain metastasis, were retrospectively identified.

Results: Seventy-two patients with 76 cavities treated from 1998 to 2006 met inclusion criteria.

A noninvasive approach for assessing tumor hypoxia in xenografts: developing a urinary marker for hypoxia.

Tumor hypoxia modifies the efficacy of conventional anticancer therapy and promotes malignant tumor progression. Human chorionic gonadotropin (hCG) is a glycoprotein secreted during pregnancy that has been used to monitor tumor burden in xenografts engineered to express this marker. We adapted this approach to use urinary beta-hCG as a secreted reporter protein for tumor hypoxia.

Interference with heme binding to histidine-rich protein-2 as an antimalarial strategy.

The erythrocytic growth stage of Plasmodium falciparum involves hemoglobin proteolysis as the primary nutrient source with the concomitant release of free heme. The liberated heme is processed by the parasite into hemozoin, a polymeric porphyrin dimer. Histidine-rich protein binds heme and mediates the formation of hemozoin, which is inhibited by the antimalarial drug chloroquine.