Hydronephrosis Caused by Polyglycolic Acid Spacer Placement Prior to Carbon Ion Radiotherapy for Local Recurrence of Rectal Cancer: Case Report

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INTRODUCTION: Carbon-ion radiotherapy (CIRT) for pelvic recurrent rectal cancer has recently attracted attention due to its excellent therapeutic outcomes. A spacer is often inserted before CIRT to ensure a certain distance between the recurrent lesion and the adjacent intestine. We report a case of hydronephrosis due to ureteral stenosis after laparoscopic insertion of a polyglycolic acid (PGA) spacer.

CASE PRESENTATION: A 58-year-old man underwent laparoscopic abdominoperineal resection and right lateral lymph node dissection after neoadjuvant chemoradiotherapy. He had been free of recurrence for 4 years. PET-CT 4.5 years after surgery revealed a 9-mm lymph node enlargement with an SUVmax = 2.88 in the left lateral region. Laparoscopic left lateral lymph node dissection was performed due to suspicion of recurrence, but removal was difficult due to severe fibrosis after previous radiation therapy. Definitive diagnosis of recurrence had not been made, so the patient was observed without treatment, but PET-CT 7 years after the initial surgery showed that the lymph node had enlarged to 25 mm with uptake of SUVmax = 8.06. Recurrence was strongly suspected, so we planned CIRT, and PGA spacer insertion was performed laparoscopically in advance. CT 3 days after insertion of the PGA spacer revealed hydronephrosis due to ureteral stenosis, which was thought to be caused by compression from the PGA spacer. Follow-up CT taken 7 days after surgery showed no improvement, so a ureteral stent was placed. Ureteral stenosis has persisted, so the ureteral stent has been replaced every 3 months. Regarding the recurrent lesions after CIRT, a tendency for them to shrink was observed on CT taken 1.5 years after the procedure.

CONCLUSIONS: In this case, a PGA spacer was inserted laparoscopically and hydronephrosis occurred early due to ureteral stenosis. Although the ureteral stenosis in the early postoperative period was thought to be caused by the PGA spacer, the persistence of ureteral stenosis was thought to be a late adverse event of CIRT. In cases where the ureter is exposed, such as after lateral lymph node dissection with neoadjuvant chemoradiotherapy, prophylactic ureteral stenting before inserting a PGA spacer may be considered.