Brachytherapy in cancer cervix: Time to move ahead from point A?

Abstract

Brachytherapy forms an integral part of the radiation therapy in cancer cervix. The dose prescription for intracavitary brachytherapy (ICBT) in cancer cervix is based on Tod and Meredith's point A and has been in practice since 1938. This was proposed at a time when accessibility to imaging technology and dose computation facilities was limited. The concept has been in practice worldwide for more than half a century and has been the fulcrum of all ICBT treatments, strategies and outcome measures. The method is simple and can be adapted by all centres practicing ICBT in cancer cervix. However, with the widespread availability of imaging techniques, clinical use of different dose-rates, availability of a host of applicators fabricated with image compatible materials, radiobiological implications of dose equivalence and its impact on tumour and organs at risk; more and more weight is being laid down on individualised image based brachytherapy. Thus, computed tomography, magnetic-resonance imaging and even positron emission computerized tomography along with brachytherapy treatment planning system are being increasingly adopted with promising outcomes. The present article reviews the evolution of dose prescription concepts in ICBT in cancer cervix and brings forward the need for image based brachytherapy to evaluate clinical outcomes. As is evident, a gradual transition from "point" based brachytherapy to "profile" based image guided brachytherapy is gaining widespread acceptance for dose prescription, reporting and outcome evaluation in the clinical practice of ICBT in cancer cervix.

Assessing dose contribution to pelvic lymph nodes in intracavitary brachytherapy for cervical cancer

“…While the use of magnetic resonance imaging (MRI)-guided 3-dimensional brachytherapy is increasing, and indeed offers several advantages over point-based treatment planning [ 1 ], many centers are unable to offer this due to logistical or financial considerations. Therefore, point-based 2-dimensional brachytherapy planning, in particular using the Manchester system, continues to be most widely employed across the world.…”

Comparison of dose volume parameters evaluated using three forward planning – optimization techniques in cervical cancer brachytherapy involving two applicators

“…Although magnetic resonance imaging (MRI) is superior to CT for the differentiation of gross tumor volume (GTV) and parametrial disease [ 14 ], CT and MRI provide basically similar quality for discrimination of bladder, rectum, sigmoid, bowel, and vagina [ 7 ]. In limited resource setting, MRI based preplanning at the first brachytherapy application and consecutive CT/MRI data fusion has been demonstrated to be safe and feasible by Dolezel et al [ 15 , 16 ]. In absence of MRI, CT scans alone when used for brachytherapy planning can ensure organs at risk (OAR) doses to be kept within acceptable limits.…”

“…In absence of MRI, CT scans alone when used for brachytherapy planning can ensure organs at risk (OAR) doses to be kept within acceptable limits. However, CT based target volumes have been overestimated as compared to MRI volumes [ 15 , 17 ].…”

Dosimetric study for cervix carcinoma treatment using intensity modulated radiation therapy (IMRT) compensation based on 3D intracavitary brachytherapy technique

“…It has been pointed out that for brachytherapy the changes in the uterine axis, uterine length, bladder, rectum filling state, and vaginal packing, could result in fluctuations in spatial location [ 53 , 54 ]. These motions could potentially affect the accurate delivery of complementary IMRT.…”