Intraoperative motive for incomplete resection in primary retroperitoneal sarcoma.

INTRODUCTION: Surgical resection is the current standard of care for retroperitoneal sarcoma (RPS). Recent data suggests that up to 5% of patient have incomplete (R2) resection. The exact reason why patients scheduled for surgery with a curative intent to treat ended up with an R2 resection is largely unknown. AIM OF THE STUDY: To identify intraoperative findings responsible for incomplete (R2) resection in primary RPS. METHODS: All records of consecutive patients scheduled for a non-metastatic primary RPS surgery between 1995 and 2020 in a tertiary care sarcoma centre were retrospective analyzed. RESULTS: Among the 347 patients scheduled for surgery, 13 (3.7%) had an incomplete (R2) resection. The reasons for incomplete surgery were intraoperative finding of vascular involvement of great vessels in 5 patients, previously undetected peritoneal metastases in 5 patients, invasion of contralateral kidney/ureter in 2 patients and the need to preserve both kidneys in 1 patient because of his past medical history. Among these patients, 3 had a laparotomy without resection and 10 had a partial resection (i.e. debulking surgery). Severe postoperative complications occurred in 5 patients. The median length of stay in hospital was 19days. After a median follow-up of 12months, the median survival of patients after incomplete resection was 18months. The 1-y, 5-y and 8-y overall survival (OS) for these patients were 46%, 14%, and 7%, respectively. CONCLUSION: Incomplete (R2) resection for a primary RPS surgery is rare in specialized sarcoma center. The next steps should be to identify the preoperative criteria that lead to this accurate selection and to define the best practice in front of a peroperative discovery of an unresectable RPS. LEVEL OF EVIDENCE: III.