Biomedical subjects

Volker W Stieber

Publications and source records attributed to Volker W Stieber.

11 recordsLinked to original sources

PubMed2006

Interim analysis of a prospective phase I/II trial of SBRT for liver metastases.

Stereotactic Body Radiation Therapy (SBRT) is a potent means of systemic cytoreductive therapy for selected patients with metastatic cancer. We here report an interim analysis of a prospective Phase I/II study of SBRT for liver metastases. Eligible patients with liver metastases met these criteria: (1) maximum tumor diameter < 6 cm; (2) < or =3 discrete lesions; (3) treatment planning confirmed > or = 700 cm3 of normal liver receives < or =15 Gy. The gross tumor volume (GTV) was expanded 5-10 mm to yield the planning target volume, which received 60 Gy in 3 fractions of SBRT over 3-14 days in the Phase II component of the trial. As of July, 2006, 36 patients have been enrolled: 18 in Phase I, 18 in Phase II. The median age was 58 years (range 27-91); the M:F ratio was 20:16. The most common primary sites were lung (n = 10), colorectal (n = 9), and breast (n = 4). Among 21 pts with > or = 6 months post-SBRT follow-up (median 19 months, range 6-29), one instance of SBRT-related grade 3 toxicity occurred in subcutaneous tissue superficial to the liver. No grade IV toxicity occurred. For 28 discrete lesions treated (median GTV 14 cm3, range 1-98) the 18 month actuarial local control estimate is 93%. This interim analysis indicates that a very high rate of durable in-field tumor control can be safely achieved with SBRT to 1-3 liver lesions as administered in this protocol, to a prescription dose of 60 Gy in 3 fractions.

Adult↗

PubMed2006

Results of a phase II trial of the GliaSite radiation therapy system for the treatment of newly diagnosed, resected single brain metastases.

OBJECT: The aim of this study was to evaluate the effectiveness of brachytherapy using the GliaSite Radiation Therapy System in patients with a newly diagnosed resected single brain metastasis. The primary end point of the study was local tumor control. The secondary end points included patient survival, distant brain recurrence, quality of life, and treatment toxicity. METHODS: The authors conducted a prospective multiinstitutional phase II study of GliaSite brachytherapy prescribed at a 60-Gy dose administered to a 1-cm depth after resection of a single brain metastasis. No whole-brain radiation therapy was given. Patients were assessed at 1 and 3 months after brachytherapy and every 3 months thereafter for up to 2 years. Seventy-one patients were enrolled at 13 centers. A GliaSite balloon catheter was implanted in 62 patients. Fifty-four patients received brachytherapy. The median patient age was 60 years. The most common tumor (54%) was non-small cell lung cancer. Fifty-seven percent of patients had brain metastasis only, whereas 43% had extracranial metastasis. The median final administered dose was 60 Gy. The magnetic resonance imaging--determined local control rate, based on several different methods, was 82 to 87%. Both the median patient survival time and the median duration of functional independence were 40 weeks. Among the 35 patients who died, the cause of death was neurological in 11%. Thirteen patients underwent reoperation for suspected tumor recurrence or radiation necrosis, and histological diagnoses included radiation necrosis without tumor (nine patients), radiation necrosis mixed with tumor (two patients), and tumor only (two patients). Extracranial metastasis, tumor size, and radiation necrosis were significant factors affecting patient survival. CONCLUSIONS: In patients with a resected single brain metastasis, GliaSite brachytherapy leads to a local control rate, median patient survival time, and duration of functional independence similar to those achieved with resection plus whole-brain radiation therapy.

Adult↗

PubMed2006

Does dose rate affect efficacy? The outcomes of 256 gamma knife surgery procedures for trigeminal neuralgia and other types of facial pain as they relate to the half-life of cobalt.

OBJECT: Gamma Knife surgery (GKS) is a treatment option for patients with refractory typical trigeminal neuralgia (TN), TN with atypical features, and atypical types of facial pain. The Gamma Knife's 201 60Co sources decay with a half-life of 5.26 years. The authors examined whether the decrease in dose rate over 4.6 years between Co source replacements affected the control rates of facial pain in patients undergoing GKS. METHODS: The authors collected complete follow-up data on 239 of 326 GKS procedures performed in patients with facial pain. Patients were classified by their type of pain. The isocenter of a 4-mm collimator helmet was targeted at the proximal trigeminal nerve root, and the dose (80-90 Gy) was prescribed at the 100% isodose line. Patients reported the amount of pain control following radiosurgery by answering a standardized questionnaire. Eighty percent of patients experienced greater than 50% pain relief, and 56% of patients experienced complete pain relief after GKS. Neither dose rate nor treatment time was significantly associated with either the control rate or degree of pain relief. A significant association between the type of facial pain and the pain control rate after GKS was observed (p < 0.001; Pearson chi-square test). In their statistical analysis, the authors accounted for changes in prescription dose over time to prevent the dose rate from being a confounding variable. There was no observable effect of the dose rate or of the treatment duration within the typical period to source replacement. CONCLUSIONS: Patients with facial pain appear to receive consistent treatment with GKS at any time during the first half-life of the Co sources.

Adult↗

PubMed2005

The role of radiosurgery in the management of malignant brain tumors.

Stereotactic radiosurgery (SRS) provides the means for creating lesions in deep-seated areas of the brain inaccessible to invasive surgery, using single high doses of focused ionizing radiation, administered using stereotactic guidance. It is a surgical technique designed to produce a specific radiobiological effect within a sharply defined target region in a single treatment session. Its technical application requires a stereotactic coordinate system, highly accurate patient repositioning (usually fixed), and multiple convergent beams of photon radiation. SRS appears to provide no benefit in the upfront treatment of newly diagnosed malignant gliomas but may be used to effectively palliate small well-demarcated volumes of recurrent disease. For selected patients with brain metastases treated with whole-brain radiation therapy (WBRT), the addition of SRS improves median survival. In selected patients with brain metastases, it is also rational to withhold WBRT in favor of radiosurgery alone, with WBRT reserved for salvage without a decrease in median survival time.

Brain Neoplasms↗

PubMed2005

Lessons learned from randomised clinical trials in adult low grade glioma.

"Lesson" is a Middle English word that has been defined as "a passage from sacred writings read in a service of worship" as well as "something learned by study or experience". The term is quite appropriate in assessment of what has been learned from randomised trials in adult low-grade gliomas, since the treatment of these tumours has traditionally been guided as much by belief as by fact. Therefore, when assessing these trials we can apply the principles of hermeneutics. Thus, the first meaning of "lesson" given here can be described as literal, whereas the second may be seen as figurative. Since hermeneutics may also refer to an in-depth analysis of a particular text, the investigators will present their interpretation of data from randomised trials. The goal is to show that the lessons learned are not necessarily literal or dogmatic but can be much more allegorical in nature.

Adult↗

PubMed2005

Glossopharyngeal neuralgia treated with gamma knife surgery: treatment outcome and failure analysis. Case report.

Glossopharyngeal neuralgia (GPN) is a rare condition in which patients present with intractable deep throat pain. Similar to trigeminal neuralgia (TN), treatment with microvascular decompression (MVD) has been successful in both. Because gamma knife surgery (GKS) has also been shown to be effective in treating TN, it seemed reasonable to apply it to GPN. The authors present the first report of GKS-treated GPN in a patient who presented with severe, poorly controlled GPN and who refused MVD.

Female↗

PubMed2004

Meningioma: current treatment options and future directions.

Benign meningiomas can be observed if not symptomatic or growing. When treatment is indicated, the options are surgery, radiosurgery, fractionated radiation therapy, or a combination of these modalities. Except in certain cases, such as large tumors that require debulking for relief of symptoms, we do not recommend the routine use of combination therapy. Intracranial meningiomas have usually been treated with surgical resection with an expected durable local control of 80% to 90% when a gross total resection (GTR) is obtained. Patients who have inoperable disease, refuse surgery, undergo less than a GTR, or who have aggressive histology should instead be considered candidates for radiation therapy or radiosurgery. While benign meningiomas can be successfully treated definitively or postoperatively with either fractionated radiation therapy or single fraction radiosurgery, atypical or malignant lesions are best treated with fractionated radiation therapy with conventional dosimetric margins. The role of systemic therapy is not yet defined, but multiple agents are being investigated in early phase trials for patients with recurrent or progressive disease after standard therapy has failed.

Combined Modality Therapy↗

PubMed2004

Current controversies in the radiotherapeutic management of adult low-grade glioma.

Over the last decade, the results of four prospective clinical trials of supratentorial low-grade glioma (LGG) in adults have been published. The data from the nearly 1,000 patients treated on these studies are summarized in this presentation, addressing the following three current controversies in the radiotherapeutic management of these patients: (1) optimum timing of radiation therapy (RT); (2) optimum RT dose; and (3) addition of chemotherapy to RT. The 5-year overall survival (OS) and progression-free survival (PFS) rates in these four studies ranged from 58% to 72% and from 37% to 55%, respectively. Significant prognostic factors included extent of surgical resection, histology, tumor size, and age. The European Organization for Research and Treatment of Cancer (EORTC) study 22845 randomized 311 adults to postoperative observation or RT. There was no difference in the 5-year OS rate between the two arms, but the irradiated patients had a significantly improved 5-year PFS rate. EORTC study 22844 randomized 379 adults to low- versus high-dose RT. Similarly, an intergroup study conducted by the North Central Cancer Treatment Group (NCCTG), Radiation Therapy Oncology Group (RTOG), and Eastern Cooperative Group (ECOG) randomized 211 adults to low- versus high-dose RT. There was no difference in the 5-year OS or PFS rates between the two dose groups in either study. A Southwest Oncology Group (SWOG) study randomized 60 adults with incompletely resected LGG to RT alone or RT plus lomustine (CCNU) chemotherapy. There was no difference in outcome between the two treatment arms. Further prospective clinical trials are needed to define the optimal management strategy for adults with supratentorial LGG. The schemata from recently completed and ongoing LGG studies will be presented.

Adult↗

PubMed2003

The use of a Leksell-BRW adapter for linac radiosurgery as an adjunct to Gamma Knife treatment.

We have investigated the use of an adapter that permits the use of a Leksell coordinate frame with a linear accelerator stereotactic radiosurgery system based on the Brown-Robert-Wells (BRW) design. This device is useful when lesions that are planned for treatment on a Leksell Gamma Knife system are found to be inaccessible to the Gamma Knife. We have found that with this device objects within a head phantom can be targeted by the linear accelerator within an accuracy of approximately 1 mm.

Brain↗

PubMed2003

Oligodendroglioma.

Oligodendroglial tumors have historically been a fatal disease, despite maximum medical and surgical treatment. However, in the past 10 years, effective adjuvant therapies have been developed that have been found to significantly prolong patient survival and, in some instances, provide a cure. Improvements in our understanding of the molecular biology of these tumors, refinements in surgical technique, and advances in chemotherapeutic treatment have combined to produce this improvement in survival with little additional toxicity to patients. At the time of diagnosis, patients should undergo maximum surgical resection or needle biopsy if maximum surgical resection is not possible. Patients with low-grade lesions may be followed, receiving radiation only at the time of progression. Patients with high-grade lesions should be irradiated up front. In addition, selected patients should receive chemotherapy. Clinical trials remain critical to advancing our understanding of these tumors and improving our ability to cure these patients.

Antineoplastic Agents, Hormonal↗

PubMed2003

Gentlemen (and ladies), choose your weapons: Gamma knife vs. linear accelerator radiosurgery.

This article compares and contrasts Gamma Knife radiosurgery with linear accelerator-based radiosurgery; where appropriate, Cyberknife technology is discussed. Topics covered are: positioning of the head (invasive versus non-invasive positioning systems); collimator construction; beam properties; beam arrangements; treatment planning; and issues regarding manpower (including a discussion of patient repositioning during treatment), machine availability, and financial considerations.

Brain Neoplasms↗