Evidence behind use of intensity-modulated radiotherapy: a systematic review of comparative clinical studies.
ABSTRACT Since its introduction more than a decade ago, intensity-modulated radiotherapy (IMRT) has spread to most radiotherapy departments worldwide for a wide range of indications. The technique has been rapidly implemented, despite an incomplete understanding of its advantages and weaknesses, the challenges of IMRT planning, delivery, and quality assurance, and the substantially increased cost compared with non-IMRT. Many publications discuss the theoretical advantages of IMRT dose distributions. However, the key question is whether the use of IMRT can be exploited to obtain a clinically relevant advantage over non-modulated external-beam radiation techniques. To investigate which level of evidence supports the routine use of IMRT for various disease sites, we did a review of clinical studies that reported on overall survival, disease-specific survival, quality of life, treatment-induced toxicity, or surrogate endpoints. This review shows evidence of reduced toxicity for various tumour sites by use of IMRT. The findings regarding local control and overall survival are generally inconclusive.
- SourceAvailable from: ncbi.nlm.nih.govFrontiers in Oncology 01/2012; 2:130. DOI:10.3389/fonc.2012.00130
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ABSTRACT: The last decades have been characterized by tremendous improvements in the treatment of rectal cancer. Based on the evidence gathered in these years, the standard treatment of patients with locally advanced rectal cancer has now become preoperative chemoradiation (CRT) followed by total mesorectal excision. Although the locoregional control with this treatment regimen is quite favorable for the majority of the patients, there is still room for further improvement. For those patients with a good response to preoperative chemoradiation (CRT), extensive surgery could be avoided and replaced by minimal invasive surgery or no surgery at all. To date however, the only way to ascertain a complete remission is pathologic examination of the resection specimen. Early response prediction of the tumor to preoperative CRT is essential for further selection of patients who could be spared invasive surgery. This could be achieved by assessing molecular markers present in the tumor tissue and blood of the patients or by non invasive functional imaging before and during preoperative treatment. For those patients with a less favorable response, treatment intensification might be the way to go. This could be accomplished by dose painting on resistant tumor regions or by the addition of molecular targeted agents to the standard treatment. In this article, we review the current standard of care and the remaining challenges in the treatment of patients with locally advanced rectal cancer.Radiotherapy and Oncology 05/2011; 100(1):15-21. DOI:10.1016/j.radonc.2011.05.024 · 4.86 Impact Factor
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ABSTRACT: Adaptive strategies in radiotherapy (RT) require the knowledge of the total dose given to every organ of the body. Because of anatomical changes and setup errors non-rigid registration is necessary to map the different dose fractions to a common reference. This study evaluates practically if the accumulation of all of these registered dose fractions must take radiobiology into account in a classical clinical setting. Ten patients with head and neck tumors treated by chemo-RT were used. Contrast-enhanced CT scans were acquired prior and during RT following delivery of mean doses of 14.2, 24.5, 35.0 and 44.9 Gy and the planned pre-treatment helical tomotherapy sinograms were applied on the per-treatment CTs to create a series of per-treatment dose distributions corresponding to each per-treatment CT image. In order to calculate the cumulative dose distribution, the per-treatment dose maps were non-rigidly deformed by using the deformation map computed by a non-rigid registration. The deformed dose maps were then summed in two ways: one while taking radiobiology into account and one without. These two strategies were compared using clinical surrogates in the target volumes (TV) and in surrounding organs at risk (OAR). The differences between the strategies, while statistically significant (p<0.05), are clinically irrelevant. In the OARs, the mean differences stay in the 0.01-0.07 Gy range for the total dose. In the targets, all mean differences stay in the 0.001-0.012 Gy range. However, some local high difference spots appear leading to punctual errors as high as 2.5 Gy. If using current radiotherapy practices and clinical recommendations based on dose surrogates computed globally on OARs and TVs, one does not need to take radiobiological effects into account while accumulating total dose as these lead to very small differences compared to a simple accumulation technique consisting of a linear sum of the dose fractions. However, care must be taken if other adaptive strategies, based on local rather than global information, are used.Radiotherapy and Oncology 07/2010; 96(1):131-8. DOI:10.1016/j.radonc.2010.05.009 · 4.86 Impact Factor