新辅助放疗（RT）采用标准技术（ST）对腹膜后肉瘤（RPS）有一定的益处。由于高风险区域（HRR）面临手术切缘和复发风险，并且远离放射敏感器官，因此使用同时集成加速（SIB）允许有针对性地提高 HRR 区域的剂量，同时避免这些器官。我们假设新辅助 SIB RT 能够改善疾病控制，而不增加毒副作用。我们回顾性地确定了 2000-2021 年间接受了新辅助 180-200cGy/分治疗标准容积（SV）的可切除非转移性 RPS 患者。SIB 患者接受了 205-230cGy/分治疗适当的 HRR。临床终点包括腹盆控制（APC）、无复发生存期（RFS）、总生存期（OS）和急性毒副作用。随访中位数为 57 个月（95%CI 50-64），共有 103 名 RPS 患者接受了 ST( n=69) 或 SIB（ n=34）RT。标准容积剂量中位数为 5000cGy(ST)，4500cGy（SIB），SIB HRR 中位数剂量为 5750cGy。脂肪肉瘤（79%与 53%，p=0.004）和 cT4 肿瘤（59%与 19%，p<0.001）在 SIB 组中更常见，手术切除率（82%与81%，p=0.88）或 R1 切缘（53.5%与50%，p=0.36）没有显著差异；没有 R2 切缘手术。与 ST 相比，SIB 显示了在 5 年 APC（96%对 70%，p=0.046）和 RFS（60.2%对 36.3%，p=0.036）方面的显著改善，而 OS 方面没有明显的益处（90.1%对 67.5%，p=0.164）。在多变量分析中，SIB 仍然是 APC（HR 0.07，95%CI 0.01-0.74; p=0.027）和 RFS（HR 0.036，95%CI 0.13-0.98; p=0.045）的预测因素。与 ST 相比，SIB 显示出毒副作用没有明显劣势，尽管整体 3 级急性毒副作用的发生率较低（3%对 22%，p=0.023）。在 RPS 中，新辅助 SIB RT 的剂量逐渐升高，可能与改善 APC 和 RFS 有独立关系，而且没有毒副作用的劣势，当与标准技术相比。由于仅标准放疗对手术的益处很少，因此我们的研究提示应考虑未来的前瞻性研究来评估 SIB RT 的益处。版权所有©2023年。Elsevier Inc.发布。

Neoadjuvant radiotherapy(RT) with standard techniques(ST) offers a modest benefit in retroperitoneal sarcoma(RPS). As the high-risk region(HRR) at risk for a positive surgical margin and recurrence is posterior and away from radiosensitive organs at risk, utilizing a simultaneous integrated boost(SIB) allows targeted dose-escalation to the HRR while sparing these organs. We hypothesized that neoadjuvant SIB RT can improve disease control compared to ST, without increasing toxicity.We retrospectively identified patients with resectable non-metastatic RPS from 2000-2021, who received neoadjuvant RT of 180-200cGy/fraction to standard volumes (SV). SIB patients received 205-230cGy/fraction to the appropriate HRR. Clinical endpoints included abdominopelvic control(APC), recurrence-free survival(RFS), overall survival(OS), and acute toxicity.With a median follow up of 57 months(95%CI 50-64), there were 103 RPS patients who received either ST(n=69) or SIB(n=34) RT. Median standard volume dose was 5000cGy(ST) and 4500cGy(SIB), with a median HRR SIB dose of 5750cGy. Liposarcomas(79% vs 53%, p=0.004) and cT4 tumors(59% vs 19%, p<0.001) were more common in the SIB cohort, without a significant difference in the rate of resection (82% vs 81%, p=0.88) or R1 margin(53.5% vs 50%, p=0.36); there were no R2 resections. SIB was associated with a significant improvement in 5-year APC(96% vs 70%, p=0.046) and RFS(60.2% vs 36.3%, p=0.036), with a non-significant OS benefit(90.1% vs 67.5%, p=0.164). On MVA, SIB remained a predictor for APC(HR 0.07, 95%CI 0.01-0.74; p=0.027) and RFS(HR 0.036, 95%CI 0.13-0.98; p=0.045). SIB showed no significant detriment in toxicity, albeit with a lower rate of overall grade 3 acute toxicity (3% vs. 22%,p=0.023), compared to ST.In RPS, dose-escalation with neoadjuvant SIB RT may be independently associated with improved APC and RFS, without a detriment in toxicity, when compared to standard techniques. The addition of standard RT having only a modest benefit to surgery alone, our study suggests that future prospective studies evaluating for the benefit of SIB RT should be considered.Copyright © 2023. Published by Elsevier Inc.