A feasibility study of IMRT for the treatment of cervical cancer patients unable to receive intracavitary brachytherapy

Women treated for cervical cancer with radiation typically receive whole pelvic radiotherapy (WPRT) followed by intracavitary brachytherapy (ICE). However, there is a subset of patients who cannot receive ICE due to advanced age, co-morbid conditions, or significant residual disease. The purpose of this study is to evaluate the use of intensity modulated radiation therapy (IMRT) as a means of treating women unable to receive ICE. The gross tumor volume (GTV), bladder and rectum were delineated on individual CT slices of patients having bulky cervical tumors. The GTV was uniformly expanded by 1-cm to produce a planning target volume (PTV). A 9-field IMRT plan was generated with the goal of providing dosimetric coverage of the PTV, while minimizing the volume of rectum and bladder irradiated. For comparison, a conventional plan (non-IM) was also generated using standard conformal techniques. The authors' analysis indicates that conventional planning results in approximately 30% of the rectal volume receiving the prescription dose. The IMRT plan limits the volume of rectum irradiated in the high dose region to less than 10%. Similarly, the bladder doses were lower with the IMRT plan compared to conventional planning. Based on the volume of normal tissues irradiated, it is expected that IMRT may provide a method of delivering potentially curative doses in women unable to receive ICE.