Neoadjuvant Simultaneous Integrated Boost Radiation Therapy Improves Clinical Outcomes for Retroperitoneal Sarcoma

Area of Science:

• Oncology
• Radiation Oncology
• Surgical Oncology

Background:

• Retroperitoneal sarcoma (RPS) treatment remains challenging, with standard neoadjuvant radiation therapy (RT) offering limited benefits.
• The high-risk region (HRR) in RPS, prone to positive surgical margins and recurrence, necessitates targeted dose escalation.
• Simultaneous integrated boost (SIB) RT allows for dose escalation to the HRR while sparing surrounding radiosensitive organs.

Purpose of the Study:

• To investigate the efficacy of neoadjuvant SIB RT in improving disease control for patients with retroperitoneal sarcoma (RPS).
• To compare the outcomes of SIB RT with standard techniques (ST) in terms of abdominopelvic control (APC), recurrence-free survival (RFS), and overall survival (OS).
• To assess the toxicity profile associated with neoadjuvant SIB RT compared to ST in RPS patients.

Main Methods:

• Retrospective analysis of 103 patients with resectable, nonmetastatic RPS treated between 2000 and 2021.
• Patients received either standard volume neoadjuvant RT (ST) or neoadjuvant SIB RT with dose escalation to the HRR.
• Clinical endpoints included APC, RFS, OS, and acute toxicity, with a median follow-up of 57 months.

Main Results:

• SIB RT was associated with a significant improvement in 5-year APC (96% vs. 70%, P=.046) and RFS (60.2% vs. 36.3%, P=.036) compared to ST.
• Multivariable analysis confirmed SIB as an independent predictor for improved APC and RFS.
• SIB RT demonstrated a lower rate of grade 3 acute toxicity (3% vs. 22%, P=.023) compared to ST, with no significant detriment.

Conclusions:

• Neoadjuvant SIB RT in RPS is independently associated with improved abdominopelvic control and recurrence-free survival.
• Dose escalation using SIB RT offers potential benefits over standard RT techniques without increasing toxicity.
• Future prospective studies are warranted to further evaluate the benefits of SIB RT in RPS management.