The use of MRI guided hypofractionated radiation to improve compliance and minimize toxicity in locally advanced cervical cancer
Faculty and Abstracts
Purpose: The standard treatment for locally advanced cervical cancer is definitive radiation (RT) with a brachytherapy boost and concurrent chemotherapy. The treatment duration is prognostic for survival; thus, it is recommended to complete this RT course within 56 days. Recent publications demonstrate improved outcomes and decreased toxicities using IMRT with daily image guidance and image-guided adaptive brachytherapy. Despite these advances, organ motion and treatment burden are continued challenges. Targeting the uterine cervix can be challenging as it is a mobile pelvic structure, with large inter and intra-fraction anatomical changes, requiring large margins to accommodate daily variations with resultant bowel toxicity. In addition, these women may face significant treatment challenges and socioeconomic barriers to care. There are limited series evaluating hypofractionated RT in patients with cervical cancer with some success, with an ongoing Canadian prospective trial evaluating the feasibility of hypofractionated CT-based radiotherapy; however, MRI-guided hypofractionated pelvic RT has not yet been explored. The major concern with hypofractionated RT is the risk of late bowel and bladder toxicity; however, this has not yet been validated. The potential benefits of improved target coverage, reduced dose to organs at risk due to tighter margins, and increased treatment compliance due to reduced treatment time make MR-Guided hypofractionated Pelvic RT an attractive approach.
Methodology: A retrospective five-year chart review of definitively treated cervical cancer patients will be completed, assessing for number treated, staging, field size, target volumes, acute/late toxicities, and treatment duration. Eligible patients will be planned for concurrent MRI-guided EBRT with weekly Cisplatin, followed by a 4-5 fraction HDR brachytherapy boost. RT planning to include IMRT to a dose of 40Gy in 15fx, treated once daily over 3 weeks. Imaging sequences will be repeated and retrospectively evaluated for radiomic features. CTCs to be collected during and following treatment, assessing for patterns and indicators to predict treatment response. Patients will complete standard HDR brachytherapy boost, utilizing daily treatment MR image for planning. Patients will undergo regular surveillance imaging to assess for tumor response. Acute and late toxicity will be assessed by physicians weekly and at follow-up. Patient reported QoL questionnaires assessing bowel, bladder, vaginal metrics, and financial toxicity to be completed prior to, during, and following treatment. Statistical analysis of data of both previously treated patients and enrolled trial patients followed by comparison of trial outcome parameters.
Results: NA
Conclusions: This study would constitute the first prospective evidence of feasibility of MRI-guided hypofractionated pelvic RT, assessing if it will lead to smaller treatment volumes, decreased toxicity, improved compliance, and improved patient reported outcomes. Hypofractionation will decrease systemic treatment burden, potentially offsetting national chemotherapy shortages. Finally, it will evaluate radiomic tumor features and CTCs and then correlate to patient outcomes.
