Less Chemo, Similar Survival in Pediatric Orbital Rhabdomyosarcoma

For children with orbital rhabdomyosarcoma (ORMS), 10-year survival has held above 90% even as international cooperative groups scaled back chemotherapy and revised radiation therapy (RT) strategies, according to a pooled analysis of nearly 700 patients treated on 11 clinical trials.¹ The findings, published in Pediatric Blood & Cancer, suggest that efforts to de-intensify therapy for this rare pediatric cancer have not come at the cost of survival, although infants and patients with metastatic disease continue to fare far worse than the broader population.

ORMS, which arises in the orbit or eyelid, accounts for about 10% of childhood rhabdomyosarcoma (RMS) cases. As the orbit's tight anatomy makes complete surgical resection difficult without significant morbidity, RT remains the primary local control modality.²

“Primary site is an important prognostic feature that, when combined with other clinical, pathologic, and molecular factors, determines a patient’s risk group and treatment,” the authors noted.¹ “The orbit is a prognostically favorable site that often accompanies other favorable prognostic features… ORMS is therefore treated with less-intensive therapy regimens.”

Outcomes Maintained Despite Less Chemo Exposure

Using the International Soft Tissue Sarcoma Consortium (INSTRuCT) database, researchers identified 679 patients with newly diagnosed ORMS enrolled across trials run by multiple groups, including the Children's Oncology Group and the European paediatric Soft tissue Sarcoma Study Group, between 1991 and 2016. Across the full cohort, 10-year event-free survival (EFS) was 74.6%, and overall survival (OS) was 92.9%. These outcomes are similar to the 77% EFS and 87% OS reported in an earlier international cohort treated from 1979 to 1992,² despite substantially lower cumulative chemotherapy exposure in the contemporary era.

In patients older than 1 year with non-alveolar (embryonal) histology and unresected tumors, who made up nearly two-thirds of the cohort (n = 425), the 10-year EFS was 78%, and the OS was 95%. Patients with localized alveolar histology, considered a higher-risk feature, had similarly favorable outcomes: 71% EFS and 88% OS at 10 years, though fusion status (a more contemporary risk marker than histology alone) was known for fewer than half of these patients.

Where Do Outcomes Still Fall Short?

Two subgroups stood out for poor prognosis. Infants younger than 1 year (n = 22) had just a 31% 5-year EFS and 61% OS, driven largely by local treatment failure. The authors pointed to previous research that found treatment for infants had high rates of treatment protocol deviation related to concerns of toxicity as a possible explanation. Patients 1 year and older with metastatic disease at diagnosis were rare (n = 5) but uniformly fatal within 4 years. The authors also found that anaplasia, present in about 18% of evaluable tumors, was associated with inferior EFS. Both infants and patients with metastatic disease were flagged as populations requiring novel therapeutic approaches.

Among patients with unresected, non-alveolar disease, EFS, but not OS, differed significantly across cooperative groups, largely tracking differences in how liberally each group applied RT. Groups that irradiated all or nearly all patients had the highest EFS, while the group that omitted RT after a complete response to chemotherapy had the lowest. Because OS did not differ, the authors said this reinforces that most patients who relapse after initial RT omission can still be salvaged. For ORMS, salvage therapy often involves additional chemotherapy, radiation, or orbital exenteration, which is a surgical procedure to remove the entire eyeball and surrounding orbital contents.

Why This Matters for Treatment Planning

EFS-focused vs OS-focused treatment philosophies may have cost-of-care implications alongside quality-of-life impacts in a population of very young, long-surviving patients. While aggressive upfront RT lowers relapse rates, it raises exposure to long-term toxicities such as cataracts and facial disfigurement. RT-sparing approaches reduce that upfront toxicity burden but shift morbidity risk toward salvage therapy upon relapse.

This latest INSTRuCT analysis follows other recent consortium efforts to standardize rare-disease pediatric RMS care. INSTRuCT expert consensus has outlined optimal management of chest wall RMS, another anatomically challenging, unfavorable-prognosis site where multidisciplinary planning and specialized surgical reconstruction were deemed essential to outcomes.³ A separate set of INSTRuCT-developed radiation guidelines for pediatric metastatic RMS similarly emphasized that combined local therapy drives the best survival in high-risk disease, while acknowledging that prospective evidence remains scarce for rare subgroups.⁴

The study authors noted that patient-level RT and chemotherapy dosing data were not available in the INSTRuCT database at the time of analysis, limiting their ability to directly attribute outcome differences to specific treatment choices.¹ In addition, the anaplasia finding was also based on a univariate analysis in a subset of patients with known anaplasia status, which may be confounded by selection bias. They called for further research into late effects, fertility, and ocular toxicity.

“Given the overall favorable prognosis of ORMS, and salvageability of patients with recurrent disease, the burden of late effects of treatment must be carefully considered and balanced with survival outcomes when contemplating any alterations in treatment strategy,” they wrote.

References

1. Metts J, Anderson J, Vokuhl C, et al. Outcomes of children with orbital rhabdomyosarcoma, 1991-2016: a report from the International Soft Tissue Sarcoma Consortium (INSTRuCT). Pediatr Blood Cancer. 2026;0:e70613. doi:10.1002/pbc.70613
2. Oberlin O, Rey A, Anderson J, et al. Treatment of orbital rhabdomyosarcoma: survival and late effects of treatment—results of an international workshop. J Clin Oncol. 2001;19(1):197-204. doi:10.1200/JCO.2001.19.1.197
3. Kaltwasser J. Consensus document outlines optimal pediatric chest wall rhabdomyosarcoma care. AJMC^®. November 13, 2025. Accessed August 21, 2026. https://www.ajmc.com/view/consensus-document-outlines-optimal-pediatric-chest-wall-rhabdomyosarcoma-care
4. Hohmann E. Experts establish radiation treatment guidelines for pediatric metastatic rhabdomyosarcoma. AJMC. May 13, 2026. Accessed August 21, 2026. https://www.ajmc.com/view/experts-establish-radiation-treatment-guidelines-for-pediatric-metastatic-rhabdomyosarcoma