E433: Modern Trends in Radiation Therapy and Their Implications on Treatment of Extremity Soft Tissue Sarcoma

The National Cancer Database (NCDB) was used to identify patients with AJCC high grade upper or lower extremity STS who underwent surgical resection and radiation from 2004-2020. Annual percent changes over time (APC) in percent of patients receiving neoadjuvant and adjuvant therapy were trended using joinpoint analysis . Multivariate regression analysis compared 30-day unplanned readmission rates and 90-day mortality rates between neoadjuvant and adjuvant groups.

Results: A total of 63,533 patients were studied.  Percentage of patients receiving neoadjuvant radiation increased significantly from 6.7% to 20.3% in patients with upper extremity STS (APC +6.73) and from 9.6% to 26.1% in patients with lower extremity STS (APC +5.6; Figure 1). Joinpoint analysis showed  a significant decline in adjuvant therapy use in both upper and lower extremity groups [APC: -1.75, -2.96 respectively].  30-day readmission rates in upper extremity STS patients were 3.9% in the neoadjuvant group and 2.2% in the adjuvant group. 90-day mortality rates in upper extremity STS were 1.8% in the neoadjuvant group and 0.6% in the adjuvant group. 30-day readmission rates in lower extremity STS patients were 4.4% in the neoadjuvant group and 2.4% in the adjuvant group. 90-day mortality rates in lower extremity STS patients were 1.8% in the neoadjuvant group and 2.1% in the adjuvant group. Five year survival data between neoadjuvant [cumulative proportion=0.65] and adjuvant groups [cumulative proportion=0.71] was significantly in favor of the adjuvant group.

Conclusions: Use of neoadjuvant radiation in the treatment of extremity STS has significantly increased during this time frame. While 30-day unplanned readmission rates for all comers and 90-day mortality rates for upper extremity disease were higher in the neoadjuvant group, these numbers remain low and represent a small number of patients. While 5-year survival data supports the use of adjuvant therapy, the difference between treatment groups may be related to a disproportionate number of patients with locally advanced STS with subsequent response to neoadjuvant radiation which then allowed for surgical resection.