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.

Regional lymph node evaluation in pediatric conventional melanoma subtype: a single-center 10-year review.

PURPOSE: To assess the prognostic and therapeutic significance of sentinel lymph node biopsy (SLNB) and completion lymph node dissection (CLND) in pediatric conventional melanoma (CM), while evaluating potential predictive factors for outcomes. METHODS: We conducted a retrospective analysis of medical records spanning 2009-2020, focusing on patients aged 18 or younger with localized cutaneous conventional melanoma. RESULTS: Among the 33 patients, SLNB detected metastasis in 57.6% of cases, with 52.6% undergoing CLND. Positive SLN patients had higher relapse risk (HR 5.92; 95% CI 1.27-27.7; P = 0.024) but similar overall survival (HR 3.19; 95% CI 0.31-33.1, P = 0.33). No significant differences in disease-free survival (DFS) and OS were found between patients who underwent CLND and those who did not (HR 1.91; 95% CI 0.49-7.43, P = 0.35, and HR 0.52; 95% CI 0.03-8.32, P = 0.64, respectively). Univariate analysis showed age at diagnosis (P = 0.02) correlated with higher recurrence risk, with a 21% hazard increase per additional year of age. CONCLUSIONS: Positive SLN status and age at diagnosis were associated with worse DFS in CM patients. Our study did not find any prognostic or therapeutic value in CLND for pediatric melanoma. Further multicenter trials are needed to confirm our single-institution experience. LEVEL OF EVIDENCE: Level IV.

Radiation therapy dose escalation achieves high rates of local control with tolerable toxicity profile in pediatric and young adult patients with Ewing sarcoma.

BACKGROUND: Local control for patients with Ewing sarcoma (EWS) who present with large tumors are suboptimal when treated with standard radiation therapy (RT) doses of 54-55.8 Gy. The purpose of this study is to determine local control and toxicity of dose-escalated RT for tumors ≥8 cm (greatest diameter at diagnosis) in pediatric and young adult patients with EWS. METHODS: Eligible patients ≤30 years old with newly diagnosed EWS ≥8 cm treated with definitive conformal or intensity modulated photon, or proton radiation therapy techniques were included. All patients in the study received dose-escalated RT doses. Outcomes included overall survival (OS), event-free survival (EFS), local failure rates, and toxicity. RESULTS: Thirty-two patients were included, 20 patients presented with metastatic disease and 12 patients with localized disease. The median RT dose was 64.8 Gy (range, 59.4-69.4 Gy) with variability of doses to protect normal surrounding tissues. All patients received systemic chemotherapy. The 5-year OS and EFS for the cohort was 64.2% and 42%, respectively. The 5-year cumulative incidence of local failure was 6.6%. There were two combined local and distant failures with no isolated local failures. Twenty-nine patients experienced short term toxicity, 90% of those being radiation dermatitis. Twenty-seven patients experienced long-term toxicity, with only one experiencing grade 4 toxicity, a secondary malignancy after therapy. CONCLUSION: This study demonstrates that definitive RT for pediatric and young adult patients with EWS ≥8 cm provides high rates of local control, while maintaining a tolerable toxicity profile.