Sciatic Nerve Preservation in Robot-Assisted Surgery for Initially Unresectable Primary Rectal Cancer: A Case Report.

Radical surgery for rectal cancer with bulky lateral pelvic lymph node (LPLN) metastasis involving the sciatic nerve presents both technical and oncological challenges. Preoperative multidisciplinary treatments have recently been anticipated to control the disease as well as to preserve organ function. A 51-year-old man, presenting with right buttock pain and impairment of walking, was diagnosed with sciatic nerve impairment due to right LPLN metastasis from rectal cancer. He was initially treated with palliative radiotherapy followed by FOLFOX plus bevacizumab. After 13 cycles of the chemotherapy, his symptoms disappeared and the LPLN shrank. Then, conversion surgery via robot-assisted low anterior resection with right LPLN dissection was performed. Although he had moderate right leg pain postoperatively, there were no motor deficits or other complications. Pathological examination of the specimen revealed microscopic residual disease at the resection margin, but he is currently surviving recurrence-free for 1.5 years. Preoperative multidisciplinary treatment enabled the preservation of the sciatic nerve in the robot-assisted conversion surgery.