Ahmed, Safia K.

AbstractPatients with resectable Ewing sarcoma (ES) in select sites, such as the pelvis or chest wall, have a higher risk of positive microscopic margins following surgery. AEWS1031 was the first North American/Australasia ES cooperative group trial allowing standardized preoperative radiotherapy, intended to minimize the morbidity of combined modality local tumor control as well as improve the likelihood of clear surgical margins. In this study, we found that the use of low‐dose preoperative radiation to a smaller target volume resulted in a high rate of R0 resection. The robust pathologic response rate strengthens existing evidence illustrating the radiosensitivity of Ewing sarcoma.

ABSTRACT Purpose Pulmonary toxicity (PT) remains a concern following total body irradiation (TBI). This study describes the incidence and factors associated with PT in a cohort of patients homogeneously treated with the lateral opposed fields technique. Methods Medical records of 61 patients ≤21 years of age treated with TBI as a component of stem cell transplantation from 1993–2017 were retrospectively reviewed. The incidences of PT, graft‐versus‐host disease (GVHD), and other toxicities were recorded for each patient. PT was subdivided into its etiologies, and symptomatic PT was established by clinical diagnosis. The association of PT with other variables was examined using chi‐square tests, and overall survival (OS) was estimated using Kaplan–Meier. Results Three‐year OS was 65% (54%–79%). Median TBI dose rate was 7.7 cGy/min (4.0–10 cGy/min). PT occurred in 20 patients (33%). A higher rate of PT was observed in patients with GVHD (65% vs. 35%, p ≤ 0.01). TBI dose rate (</≥ 7.7 cGy/min) was not associated with the risk of PT; however, on continuous analysis, a higher dose rate increased the risk of PT (HR = 1.9, p = 0.04). PT (HR = 3.4, p = 0.01), noninfectious PT (HR = 5.0, p ≤ 0.01), and pneumonitis (HR = 4.3, p = 0.01) were associated with inferior OS. Conclusions This cohort of patients treated with a low dose rate, bilateral technique, and total dose of 1000–1320 cGy experienced an acceptable incidence of PT, comparable to other published studies. Because PT correlated with reduced survival, current practice should seek to address factors associated with PT by aiming to prevent GVHD and by choosing low dose rates, such as in the range of 4.0–10 cGy/min.

Objective: Pediatric patients with non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) undergo aggressive multimodality treatment. This single institutional analysis of outcomes in this group explored factors associated with local control and survival. Methods: Patients ≤18 years old diagnosed with NRSTS between 10/1990-11/2021 who received radiotherapy (RT) were retrospectively identified. Overall Survival (OS) and disease-free survival (DFS) analyses were performed using Kaplan Meier methods. Cumulative incidence of local and distant failure were estimated. Univariate analysis was performed. Results: Fifty-one pediatric patients with NRSTS were included. Extremity tumors were most common (33/51, 65%), with 80% T1 or T2 (AJCC 8 th ) and 90% non-metastatic. Surgery in 49/51 (96%) resulted in 32 (65%) R0 resections. All received RT (median EQD2 50 Gy, range 42.4-76.9), with brachytherapy or intraoperative (IORT) boosts in 21 cases (41%) (mean EQD2 24.5 Gy). Thirty-four (66.7%) received chemotherapy. With 5.7 years median follow up, 5-year OS and DFS were 70.7% and 67.9%, respectively. Positive margins were significantly associated with worse OS on univariate analysis. Two-year local failure incidence for EBRT was 18.1% and 5.3% for EBRT+boost (HR 3.67, p=0.24). Among 6 observed local failures, 5 occurred after EBRT alone, 3 of which had positive margins. Among the EBRT+boost group, 2 had positive margins, neither with local recurrence. Conclusion: Multimodality treatment of pediatric NRSTS results in 5-year OS and DFS around 70%. R0 resection is essential to optimize outcomes in this population. Although incidence of R1 resections has declined in the modern era, IORT/brachytherapy boost may have a role in selected patients at high-risk for local recurrence.

Trends in diagnostic biopsy sample collection approaches for primary bone sarcomas have shifted in the past 2 decades. Although open/incisional biopsies used to be the predominant approach to obtain diagnostic material for Ewing sarcoma and osteosarcoma, image-guided core needle biopsies have increased in frequency and are safe for patients. These procedures are less invasive and reduce recovery times but have potential limitations. The quantity and quality of tissue obtained through these procedures vary between institutions. Acquired viable tissue volumes can be low, limiting the conduct of downstream expanded clinical workup, molecular analyses, and research. Patients with advanced Ewing sarcoma and osteosarcoma continue to have overall poor outcomes despite dose-intensive cytotoxic chemotherapy. The biology of treatment resistance is not currently well understood, partly due to limited availability of relevant tissue to study. There is a need for access to quality tumor specimens for molecular and other analyses to identify high-risk tumor subsets and drive discovery to improve patient outcomes. Given broad variability in bone tumor tissue procurement and processing across member institutions, the Children’s Oncology Group Bone Tumor Committee convened a multidisciplinary group of experts to outline the current and near-future tissue needs for optimal clinical care and access to research platforms. The goal of this working group was to provide high-level guidance on biopsy practices that safely meet these evolving needs. Harmonizing tissue collection practices is paramount to improving the care of children, adolescents, and young adults diagnosed with Ewing sarcoma and osteosarcoma.

Abstract BACKGROUND Non-germinomatous germ cell tumors (NGGCT) constitute 35%- 45% of intracranial germ cell tumors. Growing teratoma syndrome has been observed in patients with NGGCTs after starting chemotherapy. While growing teratomas are typically benign, this process can rarely involve malignant transformation and result in poor prognosis. We present the case of a patient with pineal NGGCT and growing teratoma syndrome with malignant transformation to embryonal rhabdomyosarcoma. CASE REPORT A 13-year-old male presented with headaches and vision changes. An MRI brain demonstrated a 26 x 25 x 19 mm (AP X TR X CC) mixed solid and cystic pineal mass with no evidence of metastatic disease. Due to elevated alpha fetoprotein levels in the serum and cerebrospinal fluid, he was diagnosed with intracranial NGGCT. Treatment was initiated with alternating cycles of Carboplatin/Etoposide and Ifosfamide/Etoposide. After 2 cycles of chemotherapy, a complete biochemical response was noted but MRI showed increased tumor size (presumed growing teratoma syndrome). The patient underwent complete tumor resection. Histology showed embryonal rhabdomyosarcoma as a somatic malignancy arising in a mature teratoma. Further molecular characterization revealed somatic NF1 and KRAS pathogenic mutations that are consistent with the primary diagnosis. Methylation profiling, however, did not exhibit a match with any known malignancies. Continued complete response was noted following two additional chemotherapy cycles. The patient is planned for six total chemotherapy cycles followed by high-dose craniospinal radiation with boost to the primary tumor. CONCLUSIONS Malignant transformation is a rare phenomenon in NGGCT. There is no standard of care for these patients. Further studies are needed to define ideal therapy for this patient population.

Abstract Objective . An algorithm was developed for automated positioning of lattice points within volumetric modulated arc lattice radiation therapy (VMAT LRT) planning. These points are strategically placed within the gross tumor volume (GTV) to receive high doses, adhering to specific separation rules from adjacent organs at risk (OARs). The study goals included enhancing planning safety, consistency, and efficiency while emulating human performance. Approach . A Monte Carlo-based algorithm was designed to optimize the number and arrangement of lattice points within the GTV while considering placement constraints and objectives. These constraints encompassed minimum spacing between points, distance from OARs, and longitudinal separation along the z -axis. Additionally, the algorithm included an objective to permit, at the user’s discretion, solutions with more centrally placed lattice points within the GTV. To validate its effectiveness, the automated approach was compared with manually planned treatments for 24 previous patients. Prior to clinical implementation, a failure mode and effects analysis (FMEA) was conducted to identify potential shortcomings. Main results. The automated program successfully met all placement constraints with an average execution time (over 24 plans) of 0.29 ±0.07 min per lattice point. The average lattice point density (# points per 100 c.c. of GTV) was similar for automated (0.725) compared to manual placement (0.704). The dosimetric differences between the automated and manual plans were minimal, with statistically significant differences in certain metrics like minimum dose (1.9% versus 1.4%), D5% (52.8% versus 49.4%), D95% (7.1% versus 6.2%), and Body-GTV V30% (20.7 c.c. versus 19.7 c.c.). Significance. This study underscores the feasibility of employing a straightforward Monte Carlo-based algorithm to automate the creation of spherical target structures for VMAT LRT planning. The automated method yields similar dose metrics, enhances inter-planner consistency for larger targets, and requires fewer resources and less time compared to manual placement. This approach holds promise for standardizing treatment planning in prospective patient trials and facilitating its adoption across centers seeking to implement VMAT LRT techniques.

Skull-base chordoma and chondrosarcoma are rare radioresistant tumors treated with surgical resection and/or radiotherapy. Because of the established dosimetric and biological benefits of heavy particle therapy, we performed a systematic and evidence-based review of the clinical outcomes of patients with skull-base chordoma and chondrosarcoma treated with carbon ion radiotherapy (CIRT). A literature review was performed using a MEDLINE search of all articles to date. We identified 227 studies as appropriate for review, and 24 were ultimately included. The published data illustrate that CIRT provides benchmark disease control outcomes for skull-base chordoma and chondrosarcoma, respectively, with acceptable toxicity. CIRT is an advanced treatment technique that may provide not only dosimetric benefits over conventional photon therapy but also biologic intensification to overcome mechanisms of radioresistance. Ongoing research is needed to define the magnitude of benefit, patient selection, and cost-effectiveness of CIRT compared to other forms of radiotherapy.

Background: Adolescent and young adult cancer patients are at high risk of developing radiation-associated side effects after treatment. Proton beam radiation therapy might reduce the risk of these side effects for this population without compromising treatment efficacy. Methods: We review the current literature describing the utility of proton beam radiation therapy in the treatment of central nervous system tumors, sarcomas, breast cancer and Hodgkin lymphoma for the adolescent and young adult cancer population. Results: Proton beam radiation therapy has utility for the treatment of certain cancers in the young adult population. Preliminary data suggest reduced radiation dose to normal tissues, which might reduce radiation-associated toxicities. Research is ongoing to further establish the role of proton therapy in this population. Conclusion: This report highlights the potential utility of proton beam radiation for certain adolescent young adult cancers, especially with reducing radiation doses to organs at risk and thereby potentially lowering risks of certain treatment-associated toxicities.

11529 Background: To evaluate clinical characteristics and patterns of treatment failure in patients with localized Ewing sarcoma (ES) treated on AEWS1031 according to local control (LC) strategies, tumor size, and tumor site. Methods: AEWS1031 was a phase 3 randomized trial comparing two interval compressed chemotherapy regimens. Patients who completed LC on AEWS1031 were analyzed. LC was with surgery alone (S), definitive radiation therapy (RT), or surgery plus radiation (S+RT), and determined by the treating investigator. Local failure (LF) and distant failure (DF) were defined as recurrence at primary tumor site or distant site, respectively. Fine and Gray method was used to estimate cumulative incidence of LF and DF from time LC was completed. P-values were calculated using logrank or Gray’s test, as appropriate. A two-sided p-value of ≤0.05 was considered significant. Results: 588 patients completed LC. Median age at enrollment was 13.0 years (range: 0.6- 33.9 years). Tumor sites were categorized as extremity (230; 39%), axial (142; 24%), extraosseous (110; 19%), and pelvis (106; 18%). At diagnosis, tumor volume (TV) was ≥200 mL in 170 patients (31%) and maximum tumor dimension (MTD) was ≥8 cm in 289 patients (52%). LC was with S in 320 patients (54%), RT in 160 (27%), and S+RT in 108 (18%). Eight patients received preoperative RT. Fifty-three patients (13.1%) who received S±RT had an R1 resection. LC with S was more likely for extremity (58%), RT for pelvis (38%) and S+ RT for axial (36%) and extraosseous (34%) primary tumors (p <0.01). With median follow up of 67.6 months from LC, the 5-year cumulative incidences of LF and DF for the entire cohort were 6.0% (95% CI, 4.3-8.3%) and 11.0% (95% CI, 8.6-13.9%), respectively. Eleven patients experienced simultaneous LF and DF. LF incidence was 5.0% for S, 8.4% for RT, and 5.6% for S+RT (p=0.47). DF incidence was 11.8% for S, 6.4% for RT, and 15.1% for S+RT (p=0.16). LF incidence by tumor site was 3.6% for extremity, 8.7% for pelvis, 7.3% for axial, and 6.8% for extraosseous (p=0.08). LF incidence was higher for primary tumors ≥200 mL (11.3%) compared to tumors < 200 mL (3.9%; p<0.01) and for tumors ≥8 cm (7.8%) compared to tumors < 8 cm (4.4%; p=0.02). Tumor size was associated with a higher LF incidence for S and RT, but not for S+RT (Table). LF incidence was 4.0% for R0, 7.5% for R1 with RT, and 16.7% for R1 without RT (p=0.02). Conclusions: We report the lowest LF incidence to date for prospective ES trials conducted. Both larger TV and MTD were associated with higher LF. Future investigations will aim to evaluate the impact of chemotherapy dose-intensity on LC and identify risk-stratification variables for improved LC. Five-year LF incidence by LC and tumor size. Clinical trial information: NCT01231906 . [Table: see text]