Effect of palliative radiation dose on symptom response in metastatic sarcomas.

Purpose: Palliative radiotherapy (RT) plays a crucial role in alleviating symptoms associated with metastatic sarcoma. However, there is a lack of consensus on the optimal palliative radiation dose and fractionation for metastatic sarcomas. We analyzed the association between biologically effective radiation dose and symptom response for patients who underwent palliative RT for metastatic sarcomas. Methods and materials: We retrospectively identified patients with metastatic sarcoma treated with palliative RT between 1999 and 2021 at our institution. We assessed the association between equivalent dose in 2 Gy fractions (EQD2) with an α/ß of three and symptom relief or overall survival (OS) using univariable and multivariable analyses. Results: Of the 198 metastatic sites treated, the most common indications for palliative radiation were pain (n = 181, 91 %) and compression of adjacent structures (n = 16, 8 %). In our analysis, an EQD2 of > 20 Gy was associated with greater rates of short-term symptom relief (n = 143, 85 %) at the RT site compared to an EQD2 of ≤ 20 Gy (n = 14, 54 %, P = 0.001) with no reports of grade 3 or higher toxicity. However, there was no significant improvement in short-term symptom relief for higher radiation doses. Patients treated with an EQD2 of ≤ 20 Gy had a significantly worse performance status, but there was no significant difference in overall survival based on EQD2 on multivariable analysis. Conclusions: An EQD2 ≤ 20 Gy (e.g., 8 Gy in 1 fraction) provided inadequate palliative benefit in this series. An EQD2 > 20 Gy resulted in greater rates of symptom palliation in metastatic sarcomas, but further dose escalation did not improve symptom response or durability. These findings suggest standard palliative regimens such as 20 Gy in 5 fractions (EQD2 of 28 Gy) are effective for patients with metastatic sarcomas.

Clinical features and outcomes of young patients with low-grade non-rhabdomyosarcoma soft tissue sarcomas treated with a risk-based strategy: A report from Children's Oncology Group study ARST0332.

BACKGROUND: In retrospective analyses, the Pediatric Oncology Group [POG) and the Federation National des Centres de Lutte Contre le Cancer (FNCLCC) histologic grade predict outcome in pediatric non-rhabdomyosarcoma soft tissue sarcoma (NRSTS), but prospective data on grading, clinical features, and outcomes of low-grade NRSTS are limited. METHODS: We analyzed patients less than 30 years of age enrolled on Children's Oncology Group (COG) study ARST0332 (NCT00346164) with POG grade 1 or 2 NRSTS. Low-risk patients were treated with surgery alone. Intermediate-/high-risk patients received ifosfamide/doxorubicin and radiotherapy, with definitive resection either before or after 12 weeks of chemoradiotherapy. RESULTS: Estimated 5-year event-free and overall survival were 90% and 100% low risk (n = 80), 55% and 78% intermediate risk (n = 15), and 25% and 25% high risk (n = 4). In low-risk patients, only local recurrence was seen in 10%; none with margins greater than 1 mm recurred locally. Sixteen of 17 intermediate-/high-risk patients who completed neoadjuvant chemoradiotherapy underwent gross total tumor resection, 80% with negative margins. Intermediate-/high-risk group events included one local and seven metastatic recurrences. Had the FNCLCC grading system been used to direct treatment, 29% of low-risk (surgery alone) patients would have received radiotherapy ± chemotherapy. CONCLUSIONS: Most low-risk patients with completely resected POG low-grade NRSTS are successfully treated with surgery alone, and surgical margins greater than 1 mm may be sufficient to prevent local recurrence. Patients with intermediate- and high-risk low-grade NRSTS have outcomes similar to patients with high-grade histology, and require more effective therapies. Use of the current FNCLCC grading system may result in overtreatment of low-risk NRSTS curable with surgery alone.

Embryonal sarcoma of the liver in pediatric and young adult patients: A report from Children's Oncology Group study ARST0332.

BACKGROUND: Embryonal sarcoma of the liver (ESL) is a rare mesenchymal tumor most common in childhood; the optimal treatment approach is uncertain. The clinical features and outcomes of patients with ESL enrolled in a Children's Oncology Group (COG) clinical trial that evaluated a risk-based strategy for treating soft tissue sarcomas in patients aged <30 years were evaluated. METHODS: This subset analysis included patients with ESL enrolled in COG study ARST0332. Central review of records, pathology, and imaging confirmed the diagnosis, presenting features, and surgery extent and complications. All patients received dose-intensive ifosfamide/doxorubicin chemotherapy, with cycle timing dependent on surgery and radiotherapy. Tumor resection occurred before study entry or after four cycles of chemotherapy; radiotherapy for residual tumor was optional. RESULTS: Thirty-nine eligible/evaluable patients with ESL were analyzed. All tumors were >10 cm in diameter; four were metastatic. Tumor resection was performed upfront in 23 and delayed in 16. Positive surgical margins (n = 6) and intraoperative tumor rupture (n = 6) occurred only in upfront resections. Eight patients received radiotherapy. Estimated 5-year event-free and overall survival were 79% (95% confidence interval [CI], 65%-93%) and 95% (95% CI, 87%-100%), respectively. Positive margins increased the local recurrence risk. One of 13 patients with documented hemorrhagic ascites and/or tumor rupture developed extrahepatic intra-abdominal tumor recurrence. CONCLUSIONS: The treatment strategy used in ARST0332 achieved favorable outcomes for patients with ESL despite a substantial proportion having high-risk disease features. Deferring tumor resection until after neoadjuvant chemotherapy may decrease the risk of intraoperative tumor rupture and improve the likelihood of adequate surgical margins.