Preoperative Biopsy in Patients with Retroperitoneal Sarcoma: Usage and Outcomes in a National Cohort.

INTRODUCTION Preoperative biopsy (PBx) is often recommended for retroperitoneal sarcoma (RPS), but its utilization rate and impact on perioperative management and outcomes remains undefined. METHODS Using the National Cancer Database, patients who underwent resection of non-metastatic RPS were identified (2006-2014). Patients who did and did not undergo PBx of the primary tumor were compared using propensity matching, and factors associated with survival were assessed by multivariable analysis. RESULTS Of 2620 patients, 1110 (42.4%) underwent PBx. Factors significantly associated with performance of PBx included male sex [odds ratio (OR) 1.2, P = 0.035], tumor size ≤ 5 cm (OR 1.5, P = 0.012), tumor size > 5 to ≤ 10 cm (OR 1.3, P = 0.009), non-well-differentiated liposarcoma histology (OR 2.0, P ≤ 0.001), and treatment at a high-volume center (OR 1.3, P = 0.021). Receipt of PBx was significantly associated with administration of neoadjuvant radiation (OR 8.8, P < 0.001) or systemic therapy (OR 3.3, P < 0.001), radical surgical resection (OR 1.6, P < 0.001), and complete tumor resection (OR 1.5, P < 0.003). Neoadjuvant radiation [hazard ratio (HR) 0.7, P = 0.003] and complete tumor resection (HR 0.6, P < 0.001) were significantly associated with improved overall survival (OS). Performance of PBx was not associated with OS (HR 1.1, P = 0.070), and following propensity matching, 5-year OS did not differ between the two groups (56.5% PBx vs 58.4% no PBx, P = 0.247). CONCLUSIONS A minority of patients with non-metastatic RPS undergo PBx. PBx does not negatively impact survival, but may indirectly improve outcomes in select patients by virtue of receipt of neoadjuvant therapy and attainment of complete tumor resection.