Esophageal tolerance to high-dose stereotactic ablative radiotherapy.

Dose-volume parameters are needed to guide the safe administration of stereotactic ablative radiotherapy (SABR). We report on esophageal tolerance to high-dose hypofractionated radiation in patients treated with SABR. Thirty-one patients with spine or lung tumors received single- or multiple-fraction SABR to targets less than 1 cm from the esophagus. End points evaluated include D(5cc) (minimum dose in Gy to 5 cm(3) of the esophagus receiving the highest dose), D(2cc) , D(1cc) , and D(max) (maximum dose to 0.01 cm(3) ). Multiple-fraction treatments were correlated using the linear quadratic and linear quadratic-linear/universal survival models. Three esophageal toxicity events occurred, including esophagitis (grade 2), tracheoesophageal fistula (grade 4-5), and esophageal perforation (grade 4-5). Chemotherapy was a cofactor in the high-grade events. The median time to development of esophageal toxicity was 4.1 months (range 0.6-6.1 months). Two of the three events occurred below a published D(5cc) threshold, all three were below a D(2cc) threshold, and one was below a D(max) threshold. We report a dosimetric analysis of incidental dose to the esophagus from SABR. High-dose hypofractionated radiotherapy led to a number of high-grade esophageal adverse events, suggesting that conservative parameters to protect the esophagus are necessary when SABR is used, especially in the setting of chemotherapy or prior radiotherapy.

Frameless image-guided intracranial and extracranial radiosurgery using the Cyberknife robotic system.

The Cyberknife is an image-guided robotic radiosurgery system. The image guidance system includes a kilovoltage X-ray imaging source and amorphous silica detectors. The radiation delivery device is a mobile X-band linear accelerator mounted onto a robotic arm. Through a highly complex interplay between the image guidance system, an automated couch, and the high-speed linear accelerator, near real-time tracking of the target is achieved. The Cyberknife gained Federal Drug Administration clearance in the United States in 2001 for treatment of tumors "anywhere in the body where radiation treatment is indicated." Because the Cyberknife system does not rely on rigid fixation of a stereotactic frame, tumors outside of the intracranial compartment, even those tumors that move with respiration can be treated with a similar degree of ease as intracranial targets. A description of the Cyberknife technology and a review of some of the current intracranial and extracranial applications are detailed herein.

Cerebrovascular disease in childhood cancer survivors: A Children's Oncology Group Report.

BACKGROUND: Curative therapy for childhood cancer has dramatically improved over past decades. Therapeutic radiation has been instrumental in this success. Unfortunately, irradiation is associated with untoward effects, including stroke and other cerebrovascular disease (CVD). The Children's Oncology Group (COG) has developed guidelines for screening survivors at risk for persistent or late sequelae of cancer therapy. OBJECTIVES: This review summarizes the pathophysiology and relevant manifestations of radiation-induced CVD and outlines the specific patient groups at risk for early-onset stroke. The reader will be alerted to the availability of the COG recommendations for monitoring, and, when applicable, specific screening and treatment recommendations will be highlighted. METHODS: A multidisciplinary task force critically reviewed the existing literature and scored the evidence to establish the current COG guidelines for monitoring health of survivors treated with head and neck irradiation. RESULTS: Previous head and neck exposure to therapeutic radiation is associated with latent CVD and increased risk for stroke in some patient groups. Common manifestations of radiation-induced CVD includes steno-occlusive disease, moyamoya, aneurysm, mineralizing microangiopathy, vascular malformations, and strokelike migraines. CONCLUSION: Risk for stroke is increased in survivors of pediatric CNS tumors, Hodgkin lymphoma, and acute lymphoblastic leukemia who received radiation to the brain and/or neck. As the population of survivors ages, vigilance for stroke and cerebrovascular disease needs to continue based on specific exposures during curative cancer therapy.

The role of cyberknife radiosurgery/radiotherapy for brain metastases of multiple or large-size tumors.

OBJECTIVE: Focused, highly targeted radiosurgery and fractionated radiotherapy using the Cyberknife are useful treatments for multiple or large metastases. Here we present our results of Cyberknife radiosurgery for 71 patients with 148 metastatic brain lesions. METHODS: There were 32 women and 39 men with a median age of 63 (range: 30-88) years. Radiographic follow-up was available for 60 patients with 104 lesions. The mean and median initial volumes of the tumor per lesion were 6.6 and 2.9 cm(3) (range: 0.1-53.2 cm(3)), respectively, at the time of the initial Cyberknife treatment. Forty patients (56%) had a single lesion, and 31 (44%) had multiple lesions (range: 2-7) at initial treatment. The number of fractions ranged from 1 to 3, and forty (27%) of 148 lesions were treated by a fractionated course of Cyberknife therapy. The mean marginal dose was 20.2 Gy (range 7.8-30.1 Gy, median: 20.7 Gy). RESULTS: At 44 weeks of median follow-up, there were no permanent symptoms resulting from radiation necrosis. Overall 6-month and 1-year survival rates were 74% and 47%, respectively, and the median survival time was 56 weeks. The Karnofsky performance score and extracranial metastasis were significant prognostic factors at 6 months and 1 year, respectively, in both univariate and multivariate analyses. Age or multiple metastases did not influence prognosis at 6 months and 1 year. Local control was achieved in 83% (86 lesions). After additional radiosurgical or surgical salvage, no patient died as a result of intracranial disease. Twenty-five patients developed 92 new metastases (range 1-13) outside of the treated lesions with 22.4 weeks of median follow-up. Among them, 21 patients (84 lesions) were treated by salvage Cyberknife. CONCLUSION: Despite the inclusion of an unfavorable group of patients with large tumors, our results for survival and tumor control rates are comparable to those of published series. The Cyberknife provides the advantage of allowing for fractionated treatment to multiple or large-size tumors.