Feasibility of Multiple Outpatient Interstitial Insertions Using a Hybrid Intercavitary and Interstitial Applicator for Cervical Cancer in a Freestanding Clinic

Abstract

Radiation therapy for locally advanced cervical cancer consists of external beam radiation therapy and brachytherapy. Recent introduction of image guided brachytherapy and combination intercavitary and interstitial applicators can potentially improve outcomes. Here we describe our experience with CT guided interstitial needle placement in a freestanding outpatient setting. All patients that were treated with both intercavitary and interstitial brachytherapy from June 2018 to January 2019 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, or after the first brachytherapy treatment, due to dosimetry. All tandem, ovoid and needle insertions, and HDR treatments were done in a freestanding clinic. The patients were pre-medicated with oral medication. Initially, an indwelling urinary catheter was inserted into the bladder. The tandem and ovoids were inserted the patient, and a vaginal balloon in lieu of packing. Multiple CT scans were done while advancing the interstitial needles. A final CT scan for planning was done after filling the bladder with 180 cc of diluted contrast. The patients were moved to the treatment room while treatment planning was being done, using treatment planning. After the treatment plan was approved, the bladder was refilled to 180 cc and treatment was delivered using a HDR afterloader. The applicator was removed and the patient was examined for bleeding. If any vaginal bleeding occurred, vaginal packing was inserted and pressure held. Time stamps and clinical data was collected during each procedure. 32 implants on 9 patients was performed. The median time after tandem and ovoid insertion to complete interstitial needle insertion was 10 min (mean 10, range 6-24 min), using median 3 (mean 2.75, range 1-4) CT scans and median 2 (mean 1.75, range 1-3) needles. The overall time from the initiation of the procedure to removal of the applicator and any vaginal packing was median 72 min (mean 73 min, range 61 min to 100 min). Bleeding occurred in 25% of patient, which resolved after median 3 (mean 3.38, range 1-8) minutes of vagina packing with pressure. No patients were admitted for vaginal bleeding. No patient was unable to complete her prescribed treatment due to pain or discomfort. The interstitial insertion added 10 minutes with an overall procedure time of 72 min (including insertion, planning, treatment and removal), with a 25% bleeding rate which resolves with an average of 3 min of vaginal packing and pressure. Combining intracavitary and interstitial implants using a hybrid applicator seem to be feasible, efficient, and safe in an outpatient freestanding clinic. Further study with long term toxicity data and tumor control data is warranted.