GSOR2 Presentation Time: 9:05 AM: Implementation of Hybrid Intracavitary and Interstitial Brachytherapy for Cervical Cancer in a Freestanding Clinic

Abstract

<h3>Purpose</h3> Radiation therapy for locally-advanced cervical cancer consists of external beam radiation therapy and brachytherapy. While the recent introduction of image-guided brachytherapy and hybrid intracavitary and interstitial brachytherapy treatments (HBT) may potentially improve clinical outcomes, current literature describes the procedure requiring significant resources (such as general anesthesia, conscious sedation, and MRI-based treatment planning). With increases in treatment time and patient movements, there is greater potential for positional changes of the applicator and neighboring organs at risk (OAR), which can alter dosimetry. Furthermore, these resources might not be universally available to all radiation oncology centers that perform intracavitary cervical brachytherapy, potentially limiting the widespread implementation of HBT. Here we describe our experience with CT-guided interstitial needle placement in a typical freestanding outpatient setting, with an emphasis on minimization of patient movement and treatment duration. <h3>Materials and Methods</h3> All patients that were treated with HBT from June 2018 to May 2020 were included in this series. Initially, patients were taken to the operating room, for an exam under anesthesia and Smit sleeve placement by the radiation oncologist. The patients were determined to need interstitial brachytherapy either by exam under anesthesia, due to anatomy and tumor extent, or after the first brachytherapy treatment, due to dosimetry. All tandem, ovoid and needle insertions and HDR treatments were performed in a freestanding clinic, on the CT simulator table. The patients were treated using minimal sedation (oral lorazepam and oxycodone/acetaminophen). An indwelling urinary catheter was inserted into the bladder. The tandem and ovoids (Elekta) were inserted in the patient, and a vaginal balloon was substituted for packing. Multiple CT scans were performed while advancing the interstitial needles, the bladder was filled with 180 cc of diluted contrast, and a final CT scan was taken for planning purposes. The patients were shifted from the CT table to a surgical bed (single shift), and then transported to the treatment room while treatment planning was performed using Oncentra (Elekta) treatment planning software. After the treatment plan was approved, the bladder was refilled to 180 cc and treatment was delivered using a microSelectron HDR afterloader (Elekta). The applicator was removed and the patient was examined for bleeding. If any vaginal bleeding occurred, vaginal packing was inserted with pressure applied. Time stamps and clinical data were collected during each procedure. <h3>Results</h3> Sixty-three patients underwent placement of a total of 244 interstitial implants. The median time for the entire procedure, from the time of patient entry into the CT simulation room to exit of the HDR treatment room, was 70.0 minutes (mean 70.3, range 54-100). The median time after tandem and ovoid insertion to complete interstitial needle insertion was 9.0 minutes (mean 9.8, range 4-24), using median 2 needles (mean 1.93, range 1-3) and median 3 CT scans (mean 2.63, range 1-4). Bleeding occurred in 22.1% (54/244) of implants, which resolved after median 3 minutes (mean 3.33, range 1-8) of vaginal packing with pressure. All patients (100%) required only one total shift, from the CT table to the mobile surgical bed. <h3>Conclusions</h3> In our series, the interstitial insertion portion of the HBT added 9 minutes, with an overall procedure time of 70 minutes (including insertion, planning, treatment and removal). There was an acceptable bleeding rate which quickly resolved with vaginal packing and pressure. Combining intracavitary and interstitial implants using a hybrid applicator appears to be feasible, efficient and safe in an outpatient freestanding clinic. Further studies aimed at evaluating long-term toxicities and tumor control are warranted.