Image Guided Adaptive Brachytherapy (IGABT) in Cervix Cancer

Increase of local  tumour  control  and  survival,  and  reduction  of  side  effects  are the main goals of research in modern radiation oncology. In the brachytherapy, the major technological development of the last years was the integration of 3-dimensional imaging modalities for visualization of the tumour as the primary target structure and the surrounding normal tissue where the radiation dose has to be limited. Image guided radiotherapy for cervix cancer, vaginal cancer and gynaecological recurrences became a form of targeted cancer therapy.

The radical radiotherapy for gynaecological malignancies has two major components: external beam pelvic radiotherapy (EBRT) and local brachytherapy (BT). Both treatment options are synergistic in the treatment effects, indispensable especially in the treatment of advanced stages. The role of EBRT is to deliver dose eradicating possible microscopic disease in the pelvic lymphnodes and reach gross tumour shrinkage before brachytherapy.

BT allows high local dose application. The major development in the past 10 years was the implementation of modern  imaging  for  treatment  planning  (MRI,CT).  In  2005 and 2006 the brachytherapy group of the European Society for Radiotherapy and Oncology (GEC- ESTRO) published recommendations, which aimed to support further development in this field by providing advanced concepts for structure definition and dosimetry (1,2). The introduced and defined “common” terms enabled a valid, reliable and reproducible means of communication between centres promoting this 3D approach in gynaecology. Target definition was systematically including  the  contouring  of  gross  tumour  volume  (GTV) and clinical target volumes (CTV) as well as organs at risk (OAR). Furthermore, dose-volume histogram parameters (DVH) for  the  target  (HR-CTV:  high-risk  clinical  target  volume) and OAR such as rectum, sigmoid colon and urinary bladder were introduced. The main focus of research was based on the hypothesis that the integration of 3D imaging will improve local control rates and lower side  effects  for  cervical  and  vaginal  cancer  patients  treated with radiochemotherapy and local brachytherapy. The single institutional clinical results clearly demonstrated that the systematic application of IGABT is associated with significant improvement in local control up to 95% for early stages and 85% for advanced stages, while the rate of adverse side effects remained low (<5%) (3-10). More data from ongoing multicentre prospective clinical trials will support these first observations.

References

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6. Dimopoulos JC, Pötter R, Lang S, Fidarova EF, Georg P, Dörr W, Kirisits C. Dose-effect  relationship for local control of cervical cancer by magnetic resonance image-guided   brachytherapy. Radiother Oncol. 2009; 93(2): 311-15. 
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9. Georg P, Pötter R, Georg D, Lang S, Dimopoulos JC, Sturdza A, Berger D, Kirisits C, Dörr Dose effect relationship for late side effects of the rectum and urinary bladder in magnetic resonance image-guided adaptive cervix cancer brachytherapy. Int J Radiat Oncol Biol Phys. 2012; 82(2):653-7.
10. Dimopoulos JC, Schmid MD, Fidarova E, Berger D, Kirisits C, Pötter R. Treatment of locally advanced vaginal cancer with radiochemotherapy and magnetic resonance image-guided adaptive brachytherapy: dose-volume parameters and first clinical results. Int J Radiat Oncol Biol Phys. 2012 Apr 1;82(5):1880-8.