Radiothérapie adaptative des cancers de la vessie : état de l’art et perspectives pratiques

PurposeRadiation therapy (RT) for muscle invasive bladder cancer (MIBC) is challenging, with observed variations in bladder shape and size resulting in inappropriate coverage of the target volumes (CTV). Large margins were historically applied around the CTV, increasing the dose delivered to organs at risk (OAR). With repositioning imaging and visualization of soft tissues during image guided RT, an opportunity to consider these movements and deformations appeared possible with an adaptive RT approach (ART).Materials and methodsA bibliographic search on the PubMed database has been done in January 2019. Studies focusing on patients with MIBC, treating on ART, with the objectives of feasibility, clinical and/or dosimetric evaluation and comparison with a standard irradiation technique were eligible. The purpose of this review was to define the different ART techniques used in clinical practice, to discuss their advantages compared to conventional RT in terms of target volume's coverage and OAR dose and to describe their feasibility in clinical practice.ResultsA total of 30 studies were selected. The strategies known as “composite offline”, “plan of the day” not individualized or individualized, and “re-optimization” have been identified. All the studies have shown a significant benefit of ART in target coverage and dose of OAR, especially the rectum and small bowel. All ART plans produced are not used during RT sessions. Inter-observer variability for the selection of these plans can be observed. The practical implementation within a department required staff education and training, and increases the duration of treatment preparation. The “A-POLO” approach seems to be the most suitable for practice.ConclusionART is the technique of choice for bladder cancer RT. The “plan of the day” approach, individualized according to the A-POLO methodology, seems to be the most effective. The emergence of daily re-optimization, especially using MRI-Linac, is promising. The correlation between dosimetric benefits and clinical efficacy and safety results should be demonstrated into future trials.     

Imagerie protonique pour la protonthérapie : état de l’art

Proton therapy allows a highly precise tumour volume irradiation with a low dose delivered to the healthy tissues. The steep dose gradients observed and the high treatment conformity require a precise knowledge of the proton range in matter and the target volume position relative to the beam. Thus, proton imaging allows an improvement of the treatment accuracy, and thereby, in treatment quality. Initially suggested in 1963, radiographic imaging with proton is still not used in clinical routine. The principal difficulty is the lack of spatial resolution, induced by the multiple Coulomb scattering of protons with nuclei. Moreover, its realization for all clinical locations requires relatively high energies that are previously not considered for clinical routine. Abandoned for some time in favor of X-ray technologies, research into new imaging methods using protons is back in the news because of the increase of proton radiation therapy centers in the world. This article exhibits a non-exhaustive state of the art in proton imaging.     

Cancer de l’endomètre. Application des recommandations de 2010 : étude multicentrique

ObjectiveThe endometrial cancer is the most frequent gynecological cancer. To improve and homogenize the professional practices of endometrial cancer, guidelines were developed in November 2010. The aim of this study is to estimate the implementation of these recommendations.MethodsThis is a retrospective multicentre study, using the databases of three French centers made between November 2010 and December 2012: the university hospital in Reims, the Tenon hospital in Paris and the Cancer Center Georges-François-Leclerc in Dijon. This study consists in the evaluation of the diagnoses and therapeutic assessment modalities for women with endometrial cancer and the concordance with the INCa guidelines.ResultsDuring this study, 161 patients were treated for an endometrial cancer. A histological and radiological preoperative assessment was respectively made in 92.5% and 73.3% of the cases. It revealed an agreement between anatomo-radiologic pre- and postoperative in 62.3% and 53.4% of the cases for myometrial invasion and the International Federation of Gynecology and Obstetric classification. The surgical modalities were in agreement with the guidelines in 64.6% (n = 104) and 60.3% (n = 97) of the cases. The discrepancy of the guidelines resulted from the absence or the excess realization of a lymphadenectomy. An adjuvant therapy was administered in 67.1% (n = 108) of the cases and was in agreement with the guidelines in 62.3% of the cases.Discussions The pre- and postoperative discordance between histological and radiological results are at the origin of a default in treatment for certain patients. This discordance leads to excess or lack of nodes exploration.     

Curiethérapie en France : état des lieux et perspectives économiques après l’arrêt de la commercialisation des fils d’iridium

In 2013, about 6000 patients were treated with brachytherapy, the number diminishing by 2.6% per year since 2008. Prostate, breast and gynecological cancers are the most common types of cancers. Since 2008, the number of brachytherapy facilities has decreased by 18%. In medicoeconomic terms, brachytherapy faces many problems: the coding system is outdated; brachytherapy treatments cost as much as internal radiation; fees do not cover costs; since iridium wire has disappeared from the market, the technique will be transferred to more expensive high-speed or pulse dose rates. The French financing grid based on the national study of costs lags behind changes in such treatments and in the best of cases, hospitals resorting to alternatives such as in-hospital brachytherapy are funded at 46% of their additional costs. Brachytherapy is a reference technique. With intense pressure on hospital pricing, financing brachytherapy facilities will become even more problematic as a consequence of the disappearance of iridium 192 wires. The case of brachytherapy illustrates the limits of the French financing system and raises serious doubts as to its responsiveness.     

État de l’art de l’irradiation des ganglions de la chaîne mammaire interne

In the adjuvant breast cancer treatment, postoperative radiotherapy plays a principal part with an action against the microscopic residual disease in the lymph nodes after mastectomy as well as after breast conserving surgery. This positive effect is observed also in the case of small inner lesions in patients without lymph node involvement. At the same time, there is a recognized risk of cardiac toxicity directly related to the irradiation of internal mammary nodes. This paper is a report on the current available techniques to irradiate the internal mammary nodes, including promising new technology that may help limiting the risk of cardiac toxicity.     

Imagerie TDM et IRM de l’angiogenèse tumorale

Angiogenesis is the process of activating dormant endothelial cells to form new vessels, after stimulation and it is essential in tumor growth. In many types of cancer, angiogenesis results from the activation of oncogenes that stimulate the production of Vascular Endothelial Growth Factor (VEGF). However, these newly formed vessels have a great number of abnormalities: increased density of fragile and hyperpermeable microvessels, arterial-venous shunts, caliber abnormalities and flow instabilities susceptible to flow direction inversion according to interstitial pressure. Anti-angiogenic treatments inhibit VEGF activity, perceived as structural and functional normalization of the microvascular pattern, such as reduced density of microvessels and restored morphology of the remaining ones. Conventional imaging techniques are not sensible to these changes, at best they show tumor size stabilization, hence the need of new techniques. Microvascularization imaging can be achieved by detecting functional disturbances to blood flow and not by showing the microvasculature per se. These techniques are based in quantifying the enhancement in tumor due to the passage of contrast agent after injection or protons labeled by a magnetic field. Through these measurements, one can derive interstitial and blood volumes as well as the tissue perfusion and capillary wall permeability. Microvascular imaging has greatly benefited from the improvements seen in CT and MRI equipments allowing large volume coverage with high spatial and temporal resolutions as from the evolutions in the methods to calculate, present and compare maps of the microcirculation and it’s heterogeneity. However, softwares to analyze microvascularization are still rare, limiting the technique’s application and validation in large scale. Nevertheless, imaging of the microcirculation is useful throughout the care of the oncological patient: it can reinforce the suspicious nature of a lesion, suggest anti-angiogenic treatment efficacy in hypervascular lesions, and show early treatment response before morphological changes as in RECIST criteria.     

Calcul de dose de radiothérapie à partir de tomographies coniques : état de l’art

In external beam radiotherapy, the dose planning is currently based on computed tomography (CT) images. A relation between Hounsfield numbers and electron densities (or mass densities) is necessary for dose calculation taking heterogeneities into account. In image-guided radiotherapy process, the cone beam CT is classically used for tissue visualization and registration. Cone beam CT for dose calculation is also attractive in dose reporting/monitoring perspectives and particularly in a context of dose-guided adaptive radiotherapy. The accuracy of cone beam CT-based dose calculation is limited by image characteristics such as quality, Hounsfield numbers consistency and restrictive sizes of volume acquisition. The analysis of the literature identifies three kinds of strategies for cone beam CT-based dose calculation: establishment of Hounsfield numbers versus densities curves, density override to regions of interest, and deformable registration between CT and cone beam CT images. Literature results show that discrepancies between the reference CT-based dose calculation and the cone beam CT-based dose calculation are often lower than 3%, regardless of the method. However, they can also reach 10% with unsuitable method. Even if the accuracy of the cone beam CT-based dose calculation is independent of the method, some strategies are promising but need improvements in the automating process for a routine implementation.     

Radiothérapie des cancers épidermoïdes de la tête et du cou localement évolués : état de l’art,actualités et directions futures

Therapeutic principles of radiation therapy in head and neck carcinomas will be discussed in this review. Intensity-modulated radiotherapy with concomitant cisplatin should be standard. In case of contraindication to chemotherapy, cetuximab is an option, while hyperfractionation should be considered in patients unfit for concomitant treatment. Concomitant chemotherapy should be administered in the presence of extracapsular extensions and positive margins in the postoperative setting. Current research areas such as desescalation in human papillomavirus-positive tumours, adaptive radiotherapy, radiomics and immunotherapy will also be addressed.