Dose escalation by brachytherapy for gynecological cancers.

Brachytherapy (BT), a type of focal cancer radiation therapy, delivers a highly focused dose of radiation to localized tumors, sparing surrounding normal tissue. Brachytherapy has been used to treat gynecologic malignancies, particularly cervical cancer, for over 100 years. From the first gynecologic brachytherapy treatments in the early 20th century to the modern era, significant transformations have taken place, largely due to advances in technology. The development of high-dose-rate sources, remote afterloaders, new applicators, and three-dimensional image guidance has increased tumor dose and, consequently, local control and survival, reinforcing brachytherapy's role as an integral component of gynecologic cancer treatment. Current research efforts involving biomarker research, integration of new imaging modalities, radiosensitizing therapies are aimed at further personalizing the dose delivered in BT to further improve local control and reduce treatment's related toxicities.

Discontinuous stereotactic body radiotherapy schedule increases overall survival in early-stage non-small cell lung cancer.

OBJECTIVES: The duration of stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC) may affect patient outcomes. We aimed to determine the impact of a continuous versus discontinuous SBRT schedule on local control (LC) and overall survival (OS) in NSCLC patients. MATERIALS AND METHODS: Consecutive NSCLC stage I patients (475) treated with SBRT in four centers were retrospectively analyzed. The delivered dose ranged from 48 to 75 Gy in 3-10 fractions. Based on the ratio between the treatment duration (TD) and number of fractions (n), patients were divided into two groups: continuous schedule (CS) (TD ≤ 1.6n; 239 patients) and discontinuous schedule (DS) (TD > 1.6n; 236 patients). LC and OS were compared using Cox regression analyses after propensity score matching (216 pairs). RESULTS: The median follow-up period was 41 months. Multivariate analysis showed that the DS (hazard ratio (HR): 0.42; 95 % confidence interval (CI): 0.22-0.78) and number of fractions (HR: 1.24; 95 % CI: 1.07-1.43) were significantly associated with LC. The DS (HR: 0.67; 95 % CI: 0.51-0.89), age (HR: 1.02; 95 % CI: 1-1.03), WHO performance status (HR: 2.27; 95 % CI: 1.39-3.7), and T stage (HR: 1.4; 95 % CI: 1.03-1.87) were significantly associated with OS. The 3-year LC and OS were 92 % and 64 % and 81 % and 53 % for DS and CS treatments, respectively (p < 0.01). Cox analysis confirmed that the discontinuous SBRT schedule significantly increased LC and OS. CONCLUSION: DS is associated with significantly improved LC and OS in early-stage NSCLC patients treated with SBRT.

[Circulating tumour DNA: Current detection methods, use in radiotherapy and future development]. / ADN tumoral circulant : principes, applications actuelles en radiothérapie et développement futur.

Recent technological developments enable the detection and quantification of circulating tumour DNA in the blood, with potentially major clinical implications, particularly for cancers treated with curative intent. Circulating tumour DNA has a potential impact before, during and after treatment. If limitations of this approach remain, requiring further development, it is important to know the principles and applications in view of the potential impact on the clinical practice. In this review, we will discuss the current detection methods, then the place of circulating tumour DNA in oncology and more particularly in radiotherapy.

[Doses to organs at risk for conformational and stereotactic radiotherapy: Bladder]. / 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: V60Gy<50% and maximum dose<80Gy for standard fractionation and V60Gy<5%, V48Gy<25% and V41Gy<50% for moderate hypofractionation (20 fractions of 3Gy). In case of prostate stereotactic radiotherapy (five fractions of 7.25Gy), the most frequent dose constraints in the literature are V37Gy<10cm3 and V18Gy<40%. In case of conformational radiotherapy of cervix cancer, postoperative endometrium, anal canal and rectum, the recommendations are V40Gy<40% and D2% lower than the prescribed dose.

[Dose constraints to organs at risk for conformational and stereotactic radiotherapy: Small bowel and duodenum]. / Contraintes de doses aux organes à risque en radiothérapie conformationnelle et stéréotaxique : intestin grêle et duodénum.

Radiotherapy of abdominopelvic primary or secondary lesions in conformational or stereotactic techniques is in full development. The small bowel is highly sensitive to irradiation and is the main organ at risk limiting prescription doses. This literature review aims to define the dose constraints to the small bowel and the duodenum in conformational and stereotactic body radiotherapy. The small bowel including the duodenum, jejunum and ileum is delineated on the simulation scanner. The radio-induced intestinal toxicities are acute related to the cellular depopulation of the intestinal mucosa, and late of more complex pathophysiology associating depletion in stem cells, microangiopathy, chronic inflammation and fibrosis. The main predictive factor of intestinal toxicity is the dose-volume ratio. In conformational radiotherapy, the dose constraints to the duodenum are: V25Gy<45% and V35Gy<20%. The jejunum and ileum dose constraints are for delineation by intestinal loop or peritoneal cavity respectively: V15Gy<275mL or V15Gy<830mL and V45Gy<150mL. In stereotactic body radiotherapy, small bowel dose constraints depend on fractionation and are defined on a small volume and on a maximum dose at one point. Intestinal toxicity is also dependent on factors intrinsic to the patient and radiosensitizers such as targeted therapies or chemotherapies. With the development of new techniques allowing dose escalation on the tumour and the development of inverse planning, the definition of dose constraints to the small bowel is essential for current practice.

[Interest of positioning control in onboard imaging and its delegation to the therapists]. / Intérêt du contrôle de position par imagerie embarquée et de sa délégation de l'ASN aux manipulateurs en électroradiologie médicale.

The delegation of the on board imaging position control, from the radiation oncologist to the therapist, is justified by the generalization of the image-guided radiotherapy techniques which are particularly time consuming. This delegation is however partial. Indeed, the validation of the position by the therapist can be clearly performed when the registration is based on bony landmark or fiducial. The radiation oncologist needs however to make the validation in case of large target displacement, in more complex soft tissue-based registration, and in case of stereotactic body radiation therapy. Moreover, this delegation implies at least three conditions which are first the training of the staff, then the formalization of the procedures, responsibilities and delegations and finally, the evaluation of the practices of IGRT.

[Clinical to planning target volume margins in prostate cancer radiotherapy]. / Détermination des marges du volume cible anatomoclinique au volume cible prévisionnel pour la radiothérapie du cancer prostatique.

The knowledge of inter- and intrafraction motion and deformations of the intrapelvic target volumes (prostate, seminal vesicles, prostatectomy bed and lymph nodes) as well as the main organs at risk (bladder and rectum) allow to define rational clinical to planning target volume margins, depending on the different radiotherapy techniques and their uncertainties. In case of image-guided radiotherapy, prostate margins and seminal vesicles margins can be between 5 and 10mm. The margins around the prostatectomy bed vary from 10 to 15mm and those around the lymph node clinical target volume between 7 and 10mm. Stereotactic body radiotherapy allows lower margins, which are 3 to 5mm around the prostate. Image-guided and stereotactic body radiotherapy with adequate margins allow finally moderate or extreme hypofractionation.