Integrated Intraoperative MRI-Guided Brachytherapy for Cervical Cancer: An Institutional Experience of Treatment Workflow, Planning and Patient Toxicities

Abstract

MRI planning for cervical cancer brachytherapy is associated with reduced toxicity and improved outcomes compared to historical techniques. MRI brachytherapy, however, is resource-intensive, which poses challenges in workflow and efficiency. Currently, most MRI planning protocols involve performing the brachytherapy insertion followed by patient recovery before obtaining MRI images with the patient awake. As this conventional process is lengthy and can cause patient discomfort, the goal of this study is to report the experience of an integrated MRI-based intraoperative brachytherapy program. Patients undergoing intraoperative MRI-guided brachytherapy for cervical cancer from an institutional registry trial between 2018 and 2019 were reviewed. All had intracavitary and/or interstitial brachytherapy insertion, MRI-imaging /planning, treatment delivery and applicator removal all under general anesthesia (GA). Patient, cancer and treatment-related data were abstracted. Brachytherapy specific data included applicator characteristics, dose aims, target prescriptions and organs-at-risk (OAR) doses. Pain was scored using a Likert scale from 1-10 at recovery, and at scheduled times prior to discharge. Procedure and anesthetic related toxicities at recovery and first follow-up were reviewed. Thirty-four patients with stage IBI - IIIA cervical cancers were available for analysis in this novel intraoperative program. Median age was 62 (range, 31 - 80). Eighteen patients were treated with interstitial needles for at least 1 insertion (15 hybrid, 3 perineal). The median number of needles used for fractions (Fx) 1, 2, 3 and 4 were 4, 5, 4 and 4 for hybrid applicators and 21, 21, 20 for perineal templates (3 fractions) respectively. For interstitial patients, average times for insertion (Ins), MRI imaging (MRI), planning/treatment (PlanTx) were respectively 61 +/- 14 mins, 42 +/- 8 mins, 98 +/-24 mins. Total treatment time under GA was 200 +/- 35 mins. For intracavitary patients, Ins, MRI, PlanTx times were respectively 52 +/- 14 mins, 40 +/- 10 mins, 80 +/- 17 mins, with total treatment time under GA being 172 +/- 25 mins. Mean CTVHR D90, rectum D2cc and bladder D2cc doses were 93.7.1 Gy (80.2 - 111.1), 57.9 Gy (49.7 - 67.9) and 74.9 Gy (58.7 - 86.2) respectively. There were no observed anesthetic complications, and all patients were discharged the same day. Mean pain scores post-anesthesia for interstitial patients were 0.75 (0-2), 0.95 (0 - 3.75), 0.9 (0 - 4.62) and 2.3 (0-5.4) for each consecutive fraction. For intracavitary mean pain was 0.81 (0 - 4.5), 0.59 (0 - 3.3), 0.48 (0 - 4.4) and 0.94 (0 - 4). Intraoperative MRI-based brachytherapy planning and treatment is feasible and well-tolerated with minimal pain. Interstitial procedures tended to be longer than intracavitary, but no anesthetic complications were seen. Prospective evaluation of patient toxicities, outcomes and experience is needed to evaluate this technique further.