目的： 探讨术前放射治疗（放疗）使切除困难或不可切除腹膜后软组织肉瘤病人转化治疗的效果及对预后的影响。方法： 回顾性分析2017年5月至2022年2月期间，中山医院放疗科44例切除困难或不可手术切除的原发性腹膜后软组织肉瘤病人。采用调强放疗（intensity modulated radiation therapy, IMRT）和螺旋断层放疗（tomothe-rapy, TOMO）技术，观察病人放疗后可切除转化率、预后及术后并发症发生。结果：该44例行放疗，其中IMRT 30例，TOMO 14例。治疗不良反应均为1~2级。放疗后，12例部分缓解，26例病情稳定，6例病情进展。放疗后26例行手术切除，59.1%（26/44）达到转化成可切除的目的。病人1年、3年总生存率分别为93%、72%。结论：术前放疗可有效提高初始切除困难或不可切除原发性腹膜后软组织肉瘤的可切除转化率，且术后生存率较好，不良反应轻度。

Objective: To investigate the effect of preoperative radiotherapy in the patients with primary retroperitoneal soft tissue sarcoma difficult to resect or unresectable and recognize the results of radiotherapy associated with resection and the effect of treatment on prognosis. Methods: It was analyzed retrospectively with 44 cases of primary retroperitoneal soft tissue sarcoma difficult to resect or unresectable in Department of Radiation Oncology, Zhongshan Hospital from May 2017 to February 2022. Intensity modulated radiation therapy (IMRT) and helical tomotherapy (TOMO) were used to treat the patients, and the effects of conversion to resection treatment for patients with the prognosis and complications were analyzed. Results: A total of 44 cases received radiotherapy including 30 cases with IMRT and 14 cases with TOMO. The adverse events of radiotherapy were grade 1 to 2. After preoperative radiotherapy, 12 cases achieved partial response, 26 cases remained in stable condition and 6 cases progressed. There were 26 cases treated by surgical excision after radiotherapy with the rate of conversion to resection 59.1% (26/44). The 1- and 3-year survival rates of the cases were 93% and 72% respectively. Conclusions: The preoperative radiotherapy could have improve the conversion rates of resection for the patients with primary retroperitoneal soft tissue sarcoma difficult to resect or unresectable. The better postoperative survival was gotten with mild adverse events.