Radiothérapie en conditions stéréotaxiques en pédiatrie

Stereotactic radiotherapy is a very high precision procedure, which has been limited to radiosurgery for a long time. Technological improvements allowed the development of radiotherapy in stereotactic conditions, leading to a lot of innovations. Previously indicated for cerebral pathologies, this procedure is now developed for extracerebral locations. In paediatrics, stereotactic radiotherapy is still limited, delivered precociously, due to the possibility of long-term late effects that needs to be addressed. This review reports the different useful conditions, technical evolutions, and the current validated paediatric indications, with differences from adults, and future directions.     

Radiothérapie intracérébrale en conditions stéréotaxiques

Stereotactic radiosurgery is used for treating several brain diseases. Radiosurgery is a non-invasive alternative to surgery for brain metastases, and randomized trials are on going to assess the role of radiosurgery. Radiosurgery has been advocated for patients with small benign meningioma or with vestibular schwannoma, but there is no proof of efficacy and safety of radiosurgery in comparison with other treatments. Radiosurgery can obliterate 80-90% of small arteriovenous malformations, but no information exists on the survival of treated compared with untreated patients. The limited information available suggests that radiosurgery should be fully evaluated in well-designed prospective studies.     

Radiothérapie en conditions stéréotaxiques des tumeurs bronchopulmonaires

Stereotactic radiotherapy for lung cancer is a technique that is now well established in the therapeutic arsenal. Protocols are effective, with very high local control rate and an acceptable rate of survival if one takes into account the patient's age and comorbidities. Complications are rare. This review of the literature analyses the whole process of the therapeutic indications and future prospects.     

Radiothérapie thoracique en conditions stéréotaxiques : difficultés rencontrées lors de la mise en route et solutions proposées

The aim of this paper is to describe the difficulties encountered when implementing stereotactic radiotherapy of non-small cell lung cancer (T1-T2, N0, M0) using a voluntary breath-hold technique. From 25/03/2010 to 22/02/2011, eight patients with a non-small cell lung cancer were selected for treatment. CT images were obtained with the patient maintaining breath-hold using a spirometer. Treatment was delivered when the patient maintains this level of breath-hold. Treatment was performed with a 4 MV and 10 MV photon beams from a linear accelerator Varian 2100CS, equipped with a 120 leaves collimator. 60 Gy or 48 Gy were delivered, in four sessions, to the 80% isodose. The planning target volume (PTV) was defined by adding a 5 mm margin to the internal target volume (ITV), the ITV corresponding to the gross tumour volume (GTV) plus a 3 mm margin. CTV is considered equal to GTV. The non-understanding of the gating technique, the great number of beams and the limited breath-hold times led to the failure of some treatments. It can be explained by some patients insufficient respiratory abilities and the low dose rate of one of the beams used for treatment, thus forcing some radiation fields to be delivered in two or three times. Implementing such a technique can be limited by the patients’ physical abilities and the materials used. Some solutions were found: a training phase more intense with a coaching of the breath-hold technique more precise, or the use of an abdominal compression device.     

Radiothérapie en conditions stéréotaxiques des métastases cérébrales

Stereotactic radiosurgery is now well implanted in the radiotherapy treatment tools of brain metastasis. The dose can be delivered in one or multiple sessions. Results seem equivalent. CT scan and MRI imaging are required to delineate and calculate dosimetry. Doses are variable according to the size of the metastases, localization, pathology or equipment. Stabilization or reduction of tumour size is the rules after stereotactic treatment. Impact in terms of overall survival is more difficult to apprehend because of the general context of the disease. Many questions remain unresolved, such as the usefulness of whole brain irradiation, adaptation of the treatment schedule to tumour pathophysiology, role of stereotactic treatment after surgery of metastases, etc.     

Radiothérapie en conditions stéréotaxiques des cancers bronchiques de stade I

Stereotactic body radiotherapy (SBRT) is an innovative irradiation technique which delivers high dose per fraction in a highly accurate way. It allows to treat medically inoperable patients with non-small cell lung cancer, with impressive local control rates and a very little toxicity. The different SBRT techniques available are presented in this article. Results from literature studies of SBRT for stage I non-small cell lung cancer are reviewed.     

Radiothérapie cérébrale postopératoire : indication de l’irradiation en conditions stéréotaxiques

The addition of whole-brain radiotherapy is a standard of care for patients with single, resectable intracranial metastasis. Stereotactic irradiation of the postoperative resection cavity seems to offer excellent local control rates and avoid the neurocognitive risks of whole-brain radiation therapy. The risk of remote intracranial recurrence imposes a strict surveillance imaging in order to proceed to a possible irradiation before a symptomatic stage. It must be validated in future randomized trials.     

Radiothérapie en conditions stéréotaxiques des tumeurs bénignes intracrâniennes

Stereotactic radiotherapy can be delivered in one fraction or in multiple fractions schedule. It is used in benign tumours such as meningiomas, mainly localized in the base of the skull, for acoustic schwannoma and pituitary tumours. Whatever the tumour, results with the Gamma Knife^® are the most numerous, but those obtained by linear accelerators, adapted or dedicated, are comparable. The peripheral dose is preferred to the dose delivered to the isocentre. One fraction stereotactic irradiation should be proposed in small lesions and fractionated treatment for tumours larger. Whatever the tumour, the results are satisfactory with a control rate of 90%. However, this value reflects a disparity assessment, radiological stability for meningiomas, radiological stability and preservation of useful hearing in schwannoma and radiological stability and a decrease in hormonal secretions for pituitary adenomas. Overall complication rates are low. In total, the treatment of benign lesions with stereotactic irradiation gives satisfactory results with few complications.     

Doses dans les organes à risque en radiothérapie conformationnelle et en radiothérapie en conditions stéréotaxiques : la vessie

Bladder dose constraints in case of conformational radiotherapy/intensity-modulated radiotherapy and stereotactic radiotherapy are reported from the literature, in particular from the French radiotherapy society RECORAD recommendations, according to the treated pelvic tumor sites. The dose–volume effect on urinary toxicity is not clearly demonstrated, making difficult to establish absolute dose constraints for the bladder. In case of high-dose prostate cancer radiotherapy, the bladder dose constraints are: V60 Gy < 50% and maximum dose < 80 Gy for standard fractionation and V60 Gy < 5%, V48 Gy < 25% and  V41Gy < 50% for moderate hypofractionation (20 fractions of 3 Gy). In case of prostate stereotactic radiotherapy (five fractions of 7.25 Gy), the most frequent dose constraints in the literature are V37 Gy < 10 cm³ and V18 Gy < 40%. In case of conformational radiotherapy of cervix cancer, postoperative endometrium, anal canal and rectum, the recommendations are V40 Gy < 40% and D2% lower than the prescribed dose.     

Radiothérapie en conditions stéréotaxiques des tumeurs hépatiques : état de l’art

Thanks to the improvement in radiotherapy physics, biology, computing and imaging, patients presenting with liver tumors can be efficiently treated by radiation. Radiotherapy has been included in liver tumors treatment guidelines at all disease stages. Liver stereotactic radiotherapy has to be preferred to standard fractionated radiotherapy whenever possible, as potentially more efficient because of higher biological equivalent dose. Liver stereotactic radiotherapy planning and delivery require extensive experience and optimal treatment quality at every step, thus limiting its availability to specialized centres. Multicentre studies are difficult to develop due to a large technical heterogeneity. Respiratory management, image guidance and immobilization are considerations as important as machine type. The use of multimodal planning imaging is compulsory to achieve expected contouring quality. Treatment efficacy is difficult to assess following liver stereotactic radiotherapy, but local control is high and toxicity unusual. As a consequence, liver stereotactic radiotherapy is part of multimodal and multidisciplinary management of liver tumors.     

Doses dans les organes à risque en radiothérapie conformationnelle et en radiothérapie en conditions stéréotaxiques : os et moelle osseuse

In patients undergoing external radiation therapy, bone marrow and cortical bone structures are all often neglected as organs at risk. Still, from increased febrile neutropenia risk in patients undergoing chemoradiation for a pelvic tumour to increased risk of vertebral fracture when undergoing hypofractioned stereotactic radiotherapy of a spinal metastasis, adverse effects are frequent and sometimes serious. This literature review first defines the rules for contouring these structures, then the dose constraints currently recommended. This article focuses first on conventional irradiation or intensity modulation radiotherapy considering classical fractionation. Secondly, it focuses on stereotactic radiotherapy. The considered organs will be haematopoietic structures, and bone cortical structures. Current recommendations are summarised in a table.     

Radiothérapie stéréotaxique pulmonaire : quelle machine ?

Stereotactic radiotherapy represents a fundamental change in the practice of radiotherapy of lung cancers. Despite the great heterogeneity of sites, techniques, and doses, most studies found a high local control rate, around 70 to 90% at 2 years, and reduced toxicity, around 5% of grade 3 at 2 years. Stereotactic radiotherapy can be realized either by a dedicated accelerator (CyberKnife^®) or by a conventional accelerator associated with specific systems. The two modalities deliver a very precise irradiation whose very good results published to date are similar. Some technical characteristics specific to each type of linear accelerator could guide the choice according to the target volume treated.     

Radiothérapie stéréotaxique des cancers de la prostate

Stereotactic radiotherapy is a new option in the treatment of prostate cancer. However, only retrospective series and a few prospective phase II trials are available at this moment, including a few thousands of patients with a short follow-up. Most of the protocols delivered 33 to 38 Gy in four or five fractions. Acute toxicity seems to be similar to the one observed after conventional radiotherapy. Late toxicity is less evaluable because of the short follow-up: the rate of radiation-induced proctitis seems low in the published series. Urinary toxicities are not properly evaluated: some series reported a high incidence of urinary complications grade or higher. Most of the patients belong to the D’Amico's favourable group: biochemical controls are equivalent to those observed after conventional irradiation, but the follow-up is often shorter than 5 years and no definitive conclusion could be made about the efficiency of the technique. Data for the intermediate and high risk groups are not mature. In conclusion, stereotactic radiotherapy could strongly modified the management of prostate cancer: some phase III trials have started to confirm the good results reported in preliminary series.     

Doses aux organes à risque en radiothérapie conformationnelle et en radiothérapie stéréotaxique : les poumons

Radiation-induced lung disease (RILD) is common after radiation therapy and represents cornerstone toxicities after treatment of thoracic malignancies. From a review of literature, the objective of this article was to summarize clinical and non-clinical parameters associated with the risk of RILD in the settings of normo-fractionated radiotherapy and stereotactic body radiation therapy (SBRT). For the treatment of lung cancers with a normo-fractionated treatment, the mean lung dose (MLD) should be below 15–20 Gy. For a thoracic SBRT, V20 Gy < 10% and MLD < 6 Gy are recommended. One should pay attention to central tumors and respect specific dose constraints to the bronchial tree. The recent technological improvements may represent an encouraging way to decrease lung toxicities. Finally, our team developed a calculator in order to predict the risk of radiation pneumonitis.     

Irradiations répétées de métastases cérébrales en conditions stéréotaxiques : revue de la littérature

Stereotactic radiotherapy has become a standard in the management of patients with brain metastases; its main interest is to differ whole brain radiotherapy, provider of neurocognitive toxicity and to increase the rate of local control. The repetition of radiotherapy sessions under stereotactic conditions is not codified, neither on the number of technically and clinically possible sessions, nor on the maximum total number or volume of metastases to be treated. The purpose of this review is to analyse the data in the literature concerning repeated irradiations under stereotactic conditions. The second reirradiation in stereotactic condition shows satisfactory results in terms of overall survival, local control, and toxicity. However, we lack data for patients receiving more than two sessions of SRS as well as to define dose constraints to reirradiated healthy tissues. Prospective trials are still needed to validate the management of recurrent brain metastases after initial SRS.     

Radiothérapie en conditions stéréotaxiques : étude prospective évaluant la fatigue et la qualité de vie

PurposeTo evaluate prospectively asthenia and the quality of life in patients treated by stereotactic body irradiation and to determine their predictive factors.Methods and materialsQuality of life was assessed by the EORTC QLQ-C30 and asthenia was evaluated with the Brief Fatigue Inventory (BFI), on the first day (T1), last day (T2) and 1–3 weeks after the end of treatment (T3).ResultsSixty-three patients were treated with stereotactic body irradiation from February 2017 to May 2017 and 41 were included in the analysis (22 patients excluded for lack of understanding, organization, psychologic disorders or refusal). The mean number of fractions was 5 (± 2). The compliance to quality of life assessment was 98%, 95% was 81% at T1, T2 and T3, respectively. An increase of asthenia and a worsened quality of life were found in 12 (29%) and 14 (34%) patients between T1 and T2. Univariate analysis demonstrated a correlation between asthenia and quality of life were correlated with performans status (P = 0.03 and 0.05 respectively), hemoglobin level (p = 0.01 and 0.004), albumin level (P = 0.01 and 0.06), distance between home and radiotherapy department (P = 0.05 and 0.02). Multivariate analysis demonstrated a correlation between female gender (P = 0.012), albumin level (P < 0.001), distance over 25 km (P < 0.001) with asthenia, and albumin level (P = 0.003), hemoglobin level (P = 0.004) and previous chemotherapy (P = 0.003) with quality of life. No influence of stereotactic body ratiotherapy parameters was seen.ConclusionDespite hypofractionation, stereotactic body radiotherapy induced asthenia and deterioration of quality of life.