ESTRO 2024 - Abstract Book

S2106

Clinical - Sarcoma, skin cancer, melanoma

ESTRO 2024

the difference in tumor size that in this cohort reached a median of 14 cm, compared to studies such as Roeder et al. and Calvo et al. with medians of 8 and 10 cm, respectively, and series such as Azinovic et al. where up to 80% of patients had tumor sizes smaller than 5 cm. In this study, OS at 1, 3, and 5 years was 93.9%, 87.5%, and 87.5%, respectively, which is higher than that reported in series, such as Azinovic et al., Carbó-Laso et al., Kretzler et al., in which OS rates were 64%, 64.1%, and 66%, respectively. However, these studies included a considerable proportion of patients with recurrent STS, which represented a limited number in our study (5.8%), confirming that recurrent disease is a factor that significantly influences oncologic outcomes. Regarding STS in the retroperitoneum, 43.5% were primary in our cohort. As is characteristic of the presentation of sarcomas at this level, they predominantly presented with large tumor volumes and mainly required multivisceral resections (82.5%) to obtain negative pathologic margins, which has become the standard for the treatment of this type of tumors due to the anatomical limitations within the retroperitoneum that hinder the possibility of achieving wide resection margins.With a median follow-up of 56.77 months, 47.8% of patients presented disease relapse, with 86.9% being local relapse. All patients with local relapses in our cohort were initially managed outside the INC, which indicates a differential characteristic regarding the local control of patients with primary sarcomas treated in our institution, in which there were no local relapses. The OS in patients with retroperitoneal STS at 1, 3, and 5 years was 95.7%, 82.6%, and 70.1%, respectively. Even though comparison with other retrospective series is difficult due to the heterogeneity of the studies, we obtained rates similar to the highest OS rates reported with the administration of IORT, such as that described in the study of Geischen et al and Sweeting et al. (26), with a 5-year OS of 74% and 72%, respectively.

Conclusion:

In this cohort, IORT had safe treatment with good local control rates; thus, this technique could be considered a post-radiotherapy treatment option. However, it is necessary to adequately select patients who could benefit from it. Future prospective studies could investigate additional benefits and long-term toxicity.

Keywords: Intraoperative, radiotherapy, sarcomas