Systematic review and meta-analysis of radiotherapy in various head and neck cancers: Comparing photons, carbon-ions and protons
ABSTRACT To synthesize and compare available evidence considering the effectiveness of carbon-ion, proton and photon radiotherapy for head and neck cancer.
A systematic review and meta-analyses were performed to retrieve evidence on tumor control, survival and late treatment toxicity for carbon-ion, proton and the best available photon radiotherapy.
In total 86 observational studies (74 photon, 5 carbon-ion and 7 proton) and eight comparative in-silico studies were included. For mucosal malignant melanomas, 5-year survival was significantly higher after carbon-ion therapy compared to conventional photon therapy (44% versus 25%; P-value 0.007). Also, 5-year local control after proton therapy was significantly higher for paranasal and sinonasal cancer compared to intensity modulated photon therapy (88% versus 66%; P-value 0.035). No other statistically significant differences were observed. Although poorly reported, toxicity tended to be less frequent in carbon-ion and proton studies compared to photons. In-silico studies showed a lower dose to the organs at risk, independently of the tumor site.
For carbon-ion therapy, the increased survival in mucosal malignant melanomas might suggest an advantage in treating relatively radio-resistant tumors. Except for paranasal and sinonasal cancer, survival and tumor control for proton therapy were generally similar to the best available photon radiotherapy. In agreement with included in-silico studies, limited available clinical data indicates that toxicity tends to be lower for proton compared to photon radiotherapy. Since the overall quantity and quality of data regarding carbon-ion and proton therapy is poor, we recommend the construction of an international particle therapy register to facilitate definitive comparisons.
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ABSTRACT: Radiotherapy is an important component of anti-cancer treatment. However, not all cancer patients respond to radiotherapy, and with current knowledge clinicians are unable to predict which patients are at high risk of recurrence after radiotherapy. There is therefore an urgent need for biomarkers to guide clinical decision-making. Although the importance of epigenetic alterations is widely accepted, their application as biomarkers in radiotherapy has not been studied extensively. In addition, it has been suggested that radiotherapy itself introduces epigenetic alterations. As epigenetic alterations can potentially be reversed by drug treatment, they are interesting candidate targets for anticancer therapy or radiotherapy sensitizers. The application of demethylating drugs or histone deacetylase inhibitors to sensitize patients for radiotherapy has been studied in vitro, in vivo as well as in clinical trials with promising results. This review describes the current knowledge on epigenetics in radiotherapy.Radiotherapy and Oncology 05/2014; 111(2). DOI:10.1016/j.radonc.2014.05.001 · 4.86 Impact Factor
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ABSTRACT: Radiotherapy plays an essential role in the management of head and neck squamous cell carcinoma. Radiotherapy has a distinct advantage over surgical procedures in that it could achieve organ and function preservation with an efficacy similar to that of surgical series. To improve the clinical outcomes achievable by radiotherapy, altered fractionated radiotherapy has been prospectively tested for early and intermediate risk diseases, and was previously shown to be beneficial for local control and survival. Radiotherapy alone is insufficient for locally advanced disease; therefore, concurrent chemoradiotherapy is typically performed and plays an important role. A meta-analysis (Level Ia) revealed that the concurrent use of platinum agents appeared to improve tumor control and survival; however, this was accompanied by increases in the rates of both acute and late toxicities. Regarding radiation techniques, intensity modulated radiotherapy evolved in the 1990s, and has been globally used to treat head and neck squamous cell carcinoma patients. Intensity modulated radiotherapy reduces the exposure of normal tissue to radiation while preserving excellent dose coverage to the target volume; therefore, the rate of late toxicities especially xerostomia is minimized. Small size randomized studies and a meta-analysis have provided evidence to support the benefits of intensity modulated radiotherapy over two-dimensional or three-dimensional radiation therapy. Intensity modulated radiotherapy can also preserve quality of life following definitive chemoradiotherapy. Further improvements using intensity modulated proton therapy are warranted. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: email@example.com.Japanese Journal of Clinical Oncology 12/2014; 45(3). DOI:10.1093/jjco/hyu209 · 1.75 Impact Factor
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ABSTRACT: Background Compared with photon therapy, proton-beam therapy (PBT) offers compelling advantages in physical dose distribution. Worldwide, gantry-based proton facilities are increasing in number, but no such facilities exist in Canada. To access PBT, Canadian patients must travel abroad for treatment at high cost. In the face of limited access, this report seeks to provide recommendations for the selection of patients most likely to benefit from PBT and suggests an out-of-country referral process. Methods The MEDLINE, EMBASE, PubMed, and Cochrane databases were systematically searched for studies published between January 1990 and May 2014 that evaluated clinical outcomes after PBT. A draft report developed through a review of evidence was externally reviewed and then approved by the Alberta Health Services Cancer Care Proton Therapy Guidelines steering committee. Results Proton therapy is often used to treat tumours close to radiosensitive tissues and to treat children at risk of developing significant late effects of radiation therapy (RT). In uncontrolled and retrospective studies, local control rates with PBT appear similar to, or in some cases higher than, photon RT. Randomized trials comparing equivalent doses of PBT and photon RT are not available. Summary Referral for PBT is recommended for patients who are being treated with curative intent and with an expectation for long-term survival, and who are able and willing to travel abroad to a proton facility. Commonly accepted indications for referral include chordoma and chondrosarcoma, intraocular melanoma, and solid tumours in children and adolescents who have the greatest risk for long-term sequelae. Current data do not provide sufficient evidence to recommend routine referral of patients with most head-and-neck, breast, lung, gastrointestinal tract, and pelvic cancers, including prostate cancer. It is recommended that all referrals be considered by a multidisciplinary team to select appropriate cases.Current Oncology 10/2014; 21(5):251-62. DOI:10.3747/co.21.2207 · 1.64 Impact Factor