br E mail address eric leung
E-mail address: [email protected] (E. Leung).
the available curative treatment options. Brachytherapy plays an important role in delivering conformal radiation in this scenario and common techniques use intracavitary applicators. However, intracavitary brachytherapy is limited by the conventional dose distribution and Pam3CSK4 needles are often required to help increase dose conformal-ity by positioning catheters directly into tumor tissue and thereby effectively treating large bulky tumors (1).
Perineal interstitial brachytherapy (P-ISBT) has been a specialized technique available for decades for the treat-ment of locally advanced gynecological cancers (2e5). Treatment with 3D-guided P-ISBT results in high rates of local control (6) with acceptable toxicity. However, despite this, there is reluctance to adopt this technique due to its
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apparent challenging nature and concerns of complications from the interstitial catheter needles.
There is a natural apprehension for inserting needles into the pelvis without clear image-guidance due to concerns that catheter needles may potentially intrude into organ spaces and cause severe organ injury and complications. Unlike prostate brachytherapy where transrectal ultrasound guidance can provide a clear picture of both the prostate and implant, there are limitations in visualizing the relevant anatomy in P-ISBT. Often, radiation oncologists practicing this technique rely on preoperative imaging to develop baseline treatment plans and insert needles clinically, without real-time guidance. Historically, the use of surgi-cal/laparoscopic guidance in real time was considered an essential part of interstitial brachytherapy (7,8).
This study examines a prospective cohort of gynecolog-ical oncology patients treated with clinically guided inter-stitial brachytherapy technique. Through CT evaluation, the number of needles intruding into adjacent organs was quantified and acute complications were evaluated.
Methods and materials
Between September 2014 and April 2016, 48 patients with locally advanced gynecological tumors treated with P-ISBT were enrolled into a research and ethics board approved, prospective registry trial at a single academic institution. Patients received pelvic radiotherapy before boost P-ISBT treatment or had P-ISBT as the sole modality of treatment. The combined treatment was generally given in one to two insertions with a total of three to four frac-tions of brachytherapy, while patients receiving P-ISBT alone had three to six fractions of treatment in one or two insertions.
The P-ISBT implant procedure has been previously described (9). In brief, patients undergo a prebrachytherapy MRI scan with vaginal cylinder in place. Needle location and depth of insertion are then estimated by using the pre-BT cylinder position as a reference. On the procedure day with patients under general anesthesia, gynecological examination is performed to help guide and plan needle positioning. An iodopovidone solution is used to sterilize the perineum and genitalia followed by urinary catheter insertion. A disposal perineal template applicator (Best Medical Systems, Inc., Springfield, VA) is placed over the intravaginal cylinder and against the perineum. Plastic cath-eters (6F; 24 cm length) containing metal stylets are then inserted through the template holes and obturator grooves, piercing the perineum and cervix/vaginal wall, respectively. Antibiotic prophylaxis is not mandatory and intraoperative transrectal ultrasound may be used for real-time guidance as part of their procedure. For cervical cancer patients, an intrauterine tandem is inserted inside the uterus through transabdominal ultrasound guidance followed by placement of the vaginal cylinder and needle insertion. Finally, the template is sutured against the perineum.