Developments in Stereotactic Body Radiotherapy.
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ABSTRACT:
SUBMITTER: Haridass A
PROVIDER: S-EPMC6316669 | biostudies-other | 2018 Dec
REPOSITORIES: biostudies-other
Publications
Stereotactic body radiotherapy is the technique of accurately delivering high doses of radiotherapy to small volume targets in a single or small number of sessions. The high biological effective dose of this treatment is reflected in the high rates of local control achieved across multiple tumour sites. Toxicity of the treatment can be significant and ongoing prospective trials will help define the utility of this treatment as an alternative to surgery in treating primary tumours and oligometast ...[more]
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Project description:Prostate cancer remains the most common and second most deadly cancer diagnosed amongst U.S. men. External beam radiotherapy is a standard-of-care definitive treatment option for localized prostate cancer and historically constituted an 8-9-week treatment course comprised of 39-45 doses of 1.8-2.0 Gy each (conventional fractionation, CF). Based on the notion that prostate cancer may respond favorably to a higher dose per day, considerable research efforts have been focused on characterizing the safety and efficacy profile of shorter and shorter radiation courses. Ultrahypofractionation (UHF) involves condensing the radiation course into just 5-7 treatments of 6-8 Gy each. When utilizing modern techniques that allow the precise sculpting of a dose distribution that delivers high doses to the prostate and lower doses to surrounding normal tissues over five or fewer treatments, this treatment is called stereotactic body radiotherapy (SBRT). Two randomized trials (HYPO-RT-PC and PACE-B) have compared UHF to longer radiation courses. The former demonstrated that UHF and CF have similar long-term toxicity and efficacy, while the latter demonstrated that modern SBRT has equivalent short-term toxicity as well. A separate report from a consortium of studies data provides prospective, albeit nonrandomized, data supporting the longer-term safety and efficacy of SBRT specifically. Thus, mounting high-level evidence suggests that SBRT is an acceptable standard care of option for men with localized prostate cancer.
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Project description:Stereotactic ablative radiotherapy (SABR) has developed from the principles and techniques used in the stereotactic radiosurgery treatment of brain metastases. Advances in computer technology, imaging, planning and treatment delivery and evidence from retrospective analysis of single- and multi-institutional early-phase studies have established SABR in the treatment of medically inoperable early lung cancer. Effective multidisciplinary team working is crucial to safe delivery of SABR. The variation in patient selection, radiotherapy planning and delivery techniques has led to a collective approach to SABR implementation across the UK. Centres developing the technique are represented in the UK SABR Consortium, which is supported by the relevant UK professional bodies and represents a platform to develop extracranial SABR across the UK. The uptake of SABR in the UK has been slowed by workforce issues, but at least 15 centres are currently delivering treatment with over 500 patients treated using UK SABR Consortium guidance. A mentoring program is being piloted helping new centres to develop their programs, and over 30 UK centres are expected to be offering SABR treatment by the end of 2014. The use of consistent guidance for patient selection, treatment planning and delivery in the UK gives the opportunity to collect and audit toxicity and outcome across the centres, contributing to the internationally reported SABR experience. Having established this service in the UK, the development of SABR through clinical research is a priority, and with input from the Radiotherapy Trials Quality Assurance Group, the UK is developing a national study program that includes participation in international trials.
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Project description:Prostate cancer is the most common non-cutaneous cancer in males. There are a number of options for patients with localized early stage disease, including active surveillance for low-risk disease, surgery, brachytherapy, and external beam radiotherapy. Increasingly, external beam radiotherapy, in the form of dose-escalated and moderately hypofractionated regimens, is being utilized in prostate cancer, with randomized evidence to support their use. Stereotactic body radiotherapy, which is a form of extreme hypofractionation, delivered with high precision and conformality typically over 1 to 5 fractions, offers a more contemporary approach with several advantages including being non-invasive, cost-effective, convenient for patients, and potentially improving patient access. In fact, one study has estimated that if half of the patients currently eligible for conventional fractionated radiotherapy in the United States were treated instead with stereotactic body radiotherapy, this would result in a total cost savings of US$250 million per year. There is also a strong radiobiological rationale to support its use, with prostate cancer believed to have a low ?/? ratio and therefore being preferentially sensitive to larger fraction sizes. To date, there are no published randomized trials reporting on the comparative efficacy of stereotactic body radiotherapy compared to alternative treatment modalities, although multiple randomized trials are currently accruing. Yet, early results from the randomized phase III study of HYPOfractionated RadioTherapy of intermediate risk localized Prostate Cancer (HYPO-RT-PC) trial, as well as multiple single-arm phase I/II trials, indicate low rates of late adverse effects with this approach. In patients with low- to intermediate-risk disease, excellent biochemical relapse-free survival outcomes have been reported, albeit with relatively short median follow-up times. These promising early results, coupled with the enormous potential cost savings and implications for resource availability, suggest that stereotactic body radiotherapy will take center stage in the treatment of prostate cancer in the years to come.
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Project description:Stereotactic body radiotherapy (SBRT) has become a standard treatment option for early stage, node negative non-small cell lung cancer (NSCLC) in patients who are either medically inoperable or refuse surgical resection. SBRT has high local control rates and a favorable toxicity profile relative to other surgical and non-surgical approaches. Given the excellent tumor control rates and increasing utilization of SBRT, recent efforts have focused on limiting toxicity while expanding treatment to increasingly complex patients. We review toxicities from SBRT for lung cancer, including central airway, esophageal, vascular (e.g., aorta), lung parenchyma (e.g., radiation pneumonitis), and chest wall toxicities, as well as radiation-induced neuropathies (e.g., brachial plexus, vagus nerve and recurrent laryngeal nerve). We summarize patient-related, tumor-related, dosimetric characteristics of these toxicities, review published dose constraints, and propose strategies to reduce such complications.
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Project description:For early-stage lung cancer, the treatment of choice is surgery. In patients who are not surgical candidates or are unwilling to undergo surgery, radiotherapy is the principal treatment option. Here, we review stereotactic body radiotherapy, a technique that has produced quite promising results in such patients and should be the treatment of choice, if available. We also present the major indications, technical aspects, results, and special situations related to the technique.
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Project description:Purpose: Stereotactic body radiotherapy (SBRT) is an emerging treatment modality for pancreatic ductal adenocarcinoma (PDAC) that can effectively prime cytotoxic T cells by inducing immunogenic tumor cell death in preclinical models. SBRT effects on human PDAC have yet to be thoroughly investigated, therefore, this study aimed to characterize immunomodulation in the human PDAC tumor microenvironment following therapy. Experimental Design: Tumor samples were obtained from patients with resectable PDAC. Radiotherapy was delivered a median of seven days prior to surgical resection, and sections were analyzed by multiplex IHC (mIHC), RNA-Seq, and T cell receptor sequencing (TCR-Seq). Results: Analysis of SBRT-treated tumor tissue indicated reduced tumor cell density and increased immunogenic cell death relative to untreated controls. Radiotherapy promoted collagen deposition, however, vasculature was unaffected and spatial analyses lacked evidence of T cell sequestration. Conversely, SBRT resulted in fewer tertiary lymphoid structures and failed to lessen or reprogram abundant immune suppressor populations. Higher percentages of PD-1+ T cells were observed following SBRT, and a subset of tumors displayed more clonal T cell repertoires. Conclusions: These findings suggest that SBRT augmentation of antitumor immunogenicity may be dampened by an overabundance of refractory immunosuppressive populations, and support the continued development of SBRT/immunotherapy combination for human PDAC.
2021-10-08 | GSE185311 | GEO
Project description:Prostate is the most common non-cutaneous cancer diagnosed among men in North America. Fortunately most prostate cancers are screen detected and non-metastatic on diagnosis. Treatment options for men with localized prostate cancer include surgery ± postoperative radiation or radiation ± androgen deprivation therapy (ADT). Brachytherapy ± external beam radiation treatment (EBRT) appears to have superior long-term disease control over EBRT alone likely because of higher biologic effective dose delivered. Stereotactic ablative body radiation (SABR) is a novel, non-invasive, high-precision EBRT technique that allows safe delivery of biologic doses similar to brachytherapy with similar or lower side effects [measured using toxicity or quality of life (QOL) scales]. Efficacy for SABR appears to be similar to brachytherapy including positive biopsy rates 2-3 years post treatment, biochemical failure (BF) rates out to 10-year and incidence of metastases. SABR dose escalation reduces biopsy positivity and prostate-specific antigen (PSA) nadirs but increases genitourinary (GU) and gastrointestinal (GI) toxicity-no effect on BF has been realized yet. The overall treatment time (OTT) varies in many protocols. Phase 2 randomized data shows that QOL is better in the acute setting with a weekly course of treatment compared to an every other day treatment regimen with no difference in late setting. Follow-up data are immature and likely underpowered to determine efficacy differences. SABR is cheaper and uses less resource than any other radiation technique. Given the healthcare resource challenges (including financial resources), SABR would be a welcomed addition if studies show non-inferiority to other radiation techniques. For patients with de novo or metastatic disease on relapse, there is much enthusiasm regarding the use of SABR in the setting of oligometastatic prostate cancer. SABR appears to be feasible to deliver, well tolerated and may delay the next line of therapy. However, until adequately powered randomized studies confirm a benefit, such an approach cannot be considered standard of care treatment at this time. Enrollment of eligible prostate cancer patients onto SABR clinical trials should be encouraged.
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| S-EPMC7761604 | biostudies-literature