MRLinac Boost for Gynecological Cancers if Brachytherapy is Not Feasible (MARGARITA)

Cervical Cancer, Gynecologic Cancer

Radiotherapy, MRLinac, Gynecologic Cancer, Local control, Toxicity, Cervical Cancer

The goal of this observational study is to explore the effectiveness and side effects of a high dose daily adapted SBRT (stereotactic body radiotherapy) boost delivered with MRLinac in patients with gynaecological cancers that cannot receive a brachytherapy boost to the primary tumour for different reasons (medical conditions, tumour extensions, etc). Current alternative for brachytherapy in these situations is often a non-adaptive conebeam- CT guided boost. Conebeam-CT guided non-adaptive high dose SBRT in under these circumstances is described being quite toxic. The main questions this study aims to answer are: * In how many cases could local control (i.e. total disappearance of the tumor) is be achieved with this treatment? * Which side effects are observed in patients receiving this treatment? Participants will be asked to fill out questionnaires (e.g. regarding side effects). Furthermore, participants are asked if their clinical data may be used for study purposes.

Standard treatment of locally advanced cervical cancer is chemoradiotherapy (external beam radiotherapy (EBRT) and concomitant chemotherapy with weekly Cisplatin) followed by image guided brachytherapy (IGBT). Recently, the MR Linac has emerged as new option for delivering an external beam radiotherapy boost to the primary cervical tumour after (chemo)radiaton in case brachytherapy is not feasible. MR Linac in these cases can replace traditional EBRT boosts and allow for better visualisation of the anatomy, smaller treatment margins and online treatment planning adaptation. This comes with potential for higher dose to the target and less dose to the surrounding organs. Like in IGBT, an MRL treatment provides the possibility to perform repetitive imaging before and even during each fraction and allows for dose adaptation to anatomical changes in individual patients. This way not not only the daily position of OARs in relation to the target can be taken into account, but also possible tumor regression which often is obtained during chemoradiation. Based on the experience collected so far, the MRL treatment may be an interesting treatment option in selected cases as daily MRI and plan adaptation leads to more confined dose distribution compared to CBCT-Linac options. However, dose levels for the MRL-boost are likely to be lower than for IGBT, therefore its effectiveness is still unsure. Aims of the study: * To introduce MRL-boost in locally advanced cervical cancer in a multicenter setting within the frame of a prospective observational study. * To establish a bench-mark for clinical outcome with MRL-boost in a multi-center patient population with respect to local control, survival and toxicity. * To establish reference material with regard to MRL-based DVH parameters; if applicable delineations according to the guidelines from the GEC-ESTRO gynecology working group will be used. * To report image-based DVH parameters for target (GTV, CTV, PTV) and for OARs * To report recurrence patterns * To report Quality of Life Type of design This study is a multicenter prospective observational study. Patient registration and dosimetric reporting will be performed in the individual centers.

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Denmark, Netherlands