Robotic-assisted Intraoperative High-dose Rate Remote Brachytherapy Following Laparoscopic Robotic-assisted Resection of Pelvic Recurrence of Urethral Carcinoma

Abstract

In 2014, a 64-year-old woman was diagnosed with urethral adenocarcinoma invading the anterior mid-vagina. She underwent pelvic exenteration, bilateral pelvic lymph node dissection, and ileal conduit urinary diversion in October 2014 at an outside facility. Surgical pathology results revealed pT3N0 moderately differentiated adenocarcinoma with negative margins. The patient did not receive adjuvant chemotherapy or radiation. Restaging scans in January 2015 showed a solitary enlarging right upper lobe pulmonary nodule, and a positron emission tomography (PET) scan showed intense uptake in the right upper lobe pleural-based pulmonary nodule. The patient had a right upper lobe wedge resection on February 9, 2015, and the pathology results were consistent with metastatic adenocarcinoma, likely related to the urethral primary. The surgical margins were negative. A repeat PET scan on March 30, 2015 showed new hypermetabolic pulmonary nodules bilaterally, concerning for metastatic disease. On April 21, 2015, the patient started on carboplatin and paclitaxel and completed 3 total cycles. Because of significant side effects, including neutropenia, the patient could not tolerate the chemotherapy regimen and was switched to nivolumab. Before starting nivolumab, a computed tomography (CT) chest scan showed an interval increased size of the bilateral pulmonary nodules when compared with prior PET/CT and increased size of a precarinal mediastinal lymph node. After 15 cycles of nivolumab, the patient exhibited a partial clinical response on the basis of the Response Evaluation Criteria in Solid Tumors in the lungs and mediastinum, and she remained with stable disease while on nivolumab. In 2016, the patient had to discontinue nivolumab because of pneumonitis. She remained off of systemic therapies with no evidence of progression until October 2017, when re-staging CT and magnetic resonance imaging showed a 3 cm mass in the pelvic floor along the right peri-vaginal area, concerning for local recurrence. The mass was just anterior to the vaginal remnant and posterior to the pubic bone (Fig 1). At that time, the patient was asymptomatic. The initial plan was to treat this likely recurrent lesion with stereotactic radiation therapy (SBRT). However, the tumor mass was immediately adjacent to the small bowel (Fig 2). The patient was simulated in the prone position on a belly board, but the small bowel did not change position. Therefore, SBRT was deemed not feasible. The treatment team and patient decided to move forward with robotic surgery and intraoperative high-dose-rate remote brachytherapy. After intravenous prophylactic antibiotics were administered, general anesthesia was induced. A pelvic examination revealed a 4 cm mass in the right pelvis invading into the proximal vagina but not into the pelvic side wall. Standard laparoscopic access was performed using the Veress needle technique. Adhesions were identified and taken down systematically. Four robotic ports and 2 assistant ports (10-12 and 5 mm, respectively) were used. The patient was placed in the Trendelenburg position, and the robot was docked. Loops of bowel were freed from the abdominal wall and the pelvis. The right pelvic mass was then resected robotically, along with part of the muscles of the pelvic floor and the right lateral vaginal cuff wall. The specimen was placed in an endobag and removed through the vagina. After resection of the mass, the area of risk was visualized by the superior (cranial to caudal direction) robotic camera. The risk area involved the area adjacent to the right inferior pubic ramus, right anterior pubic arch, and left anterior pubic arch. The area adjacent to the left inferior pubic ramus was not at risk. Two layers of 1.65 mm of lead (1 layer folded in half) were placed through the vaginal opening. The robotic arm was utilized to position the lead over the bowel for shielding from intraoperative radiation. The vaginal cylinder (3.5 cm diameter) was pla