(P 291) INTRA-ARTERIAL CHEMOTHERAPY WITH CONCOMITANT RADIATION THERAPY FOR UNRESECTABLE SARCOMA

Objective: We have performed intra-arterial chemotherapy with concomitant radiation therapy (IACRT) for long-term local control and symptom palliation of bone and soft tissue sarcomas which are large and not resectable in our institution. The objective of this study is to clarify the outcomes of IACRT.

Methods: Fifty sarcoma patients with mean age of 59.3 years who received IACRT at single institution from 2002 to 2024 were enrolled. We have retrospectively collected the patient characteristics, treatment details, radiological findings and clinical outcomes, and analyzed availability and issues of IACRT.

Results: Twenty-one bone and 29 soft tissue sarcomas were included. The tumor locations were the pelvis, lower extremities and chest wall, in 32, 17 and 1 case, respectively. The mean tumor size was 13.0 cm. The median follow-up period was 23.5 months, and oncologic outcomes were AWD/NED in 12 and DOD/DOOD in 38 patients. Forty-two patients received cisplatin as the most common drug used in IACRT, with a mean administration number of 4.1 times. Twenty-eight and 22 patients received photon and proton beam radiotherapy, respectively, with a mean total dose of 62.7 Gy(E). The 2-years and 5-years overall survival was 51.0% and 17.9%, and the local control rate was 65.0% and 35.7%, respectively. Nausea, anemia and diarrhea as acute complications, and enteritis/bleeding and peripheral neurological disturbance as delayed complications were observed. Most alive cases (77.8%) showed 0 to 1 of performance status at the final observation. Statistical analyses revealed the local control was significantly related to patients’ survival (p=0.041), and the intra-arterial administration number was an important factor (p=0.001). All 6 patients who survived more than 5 years (6.4-17 years) were without distant metastasis before treatment, 3 or more times of intra-arterial cisplatin, more than cumulative 200 mg/m2, and a dose of 66 Gy(E) or more with proton beam therapy.

Conclusion: This study suggests that IACRT may be a promising treatment for unresectable sarcomas. Further study is needed to establish the indication and protocols of IACRT according to the purpose, and to search for biomarkers to predict treatment efficacy.