Ewing Sarcoma: Symptoms, Stages, and Treatment

Ewing sarcoma comes from a bone marrow-derived mesenchymal stem cell. It can grow in bone or in soft tissue.

Several older names describe the same tumor. Peripheral primitive neuroectodermal tumor is one. Askin tumor means Ewing sarcoma of the chest wall. Extraosseous Ewing sarcoma means a tumor outside bone. Older records may also use the phrase Ewing sarcoma family of tumors.

In 2020 the World Health Organization redrew the boundary. Ewing sarcoma now sits in a chapter on undifferentiated small round cell sarcomas, alongside three separate groups: sarcomas with EWSR1 fusions to non-ETS partners, CIC-rearranged sarcoma, and sarcomas with BCOR changes. Those three used to be lumped in as translocation-negative Ewing sarcoma. They are now tracked separately, even when treated the same way.

For decades the answer was a microscope. Pathologists looked for small, round, blue cells and confirmed with CD99 staining.

Genetics sharpened that. Most Ewing sarcomas carry a t(11;22) translocation. It joins part of the EWSR1 gene to a gene in the ETS family, most often FLI1. The fused gene makes a transcript that drives the cancer.

That is why molecular testing matters at diagnosis. Two tumors can look the same under glass and belong in different categories.

US incidence is 3.0 cases per million people under 20, and it has not changed since the 1973 to 2004 period. Rates climb through childhood:

• Under 1 year: 0.5 per million.
• Ages 1 to 4: 1.0 per million.
• Ages 5 to 9: 2.3 per million.
• Ages 10 to 14: 4.3 per million.
• Ages 15 to 19: 4.5 per million.

The split by sex is close to 58% male and 42% female in US data. Incidence is nine times higher in White people than in Black people, with Asian people in between. Part of that gap may trace to a variant in the EGR2 gene, which appears to amplify the effect of the EWSR1::FLI1 fusion and is far more common in White populations.

Ewing sarcoma is usually not inherited. One recent analysis did find that heterozygous harmful variants in the FANCC gene were enriched in Ewing sarcoma patients compared with cancer-free controls, in both a discovery and a validation cohort.

NCI publishes a site breakdown, and it is more spread out than most people expect:

• Soft tissue: 19%.
• Pelvis: 18%.
• Tibia, fibula, patella, foot: 14%.
• Rib: 11%.
• Femur: 11%.
• Spine: 7%.
• Humerus: 7%.
• Skull: 5%.
• Sternum, scapula, clavicle: 5%.
• Radius, ulna, hand: 2%.

Symptoms follow the site: swelling and pain near the tumor, sometimes a fracture from a minor injury, sometimes fever, fatigue, weight loss, or anemia.

The gap between the first symptom and the diagnosis is long. NCI reports a median of 2 to 5 months. It runs longer for older patients and for pelvic tumors.

Here is the part worth holding onto. That delay has not been linked to whether the cancer had spread, to surgical outcome, or to survival. A slow path to diagnosis is common in this disease and does not by itself change what follows.

Ewing sarcoma is grouped as localized, metastatic, or recurrent. The workup NCI lists:

• MRI of the primary tumor site.
• CT scan of the chest.
• PET scan. Many investigators now use PET in place of a bone scan.
• Bone marrow aspiration and biopsy.
• X-ray of primary bone sites.
• Complete blood count, and blood chemistry including lactate dehydrogenase.

Two details matter. Imaging covers the entire involved bone, because skip metastases — separate deposits in the same bone — were found in 15.8% of patients in one study, and their presence signals higher risk of distant spread. And bone marrow biopsy may be skipped in otherwise localized disease when FDG PET is used. Pooled data put bone marrow metastasis at 4.8% of all new diagnoses, 17.5% among those with metastatic disease, and the only metastatic site in just 1.2%.

About 25% of patients already have metastases at diagnosis. Lung, bone, and bone marrow are the usual sites.

Nearly everyone gets both chemotherapy and local treatment. The reason is blunt: most patients whose disease looks localized already have hidden spread.

The US standard is VDC alternating with IE. VDC is vincristine, doxorubicin, and cyclophosphamide. IE is ifosfamide and etoposide.

Two trials set the current schedule.

A Children's Oncology Group trial randomly assigned patients with newly diagnosed localized disease to VDC/IE every 2 weeks or every 3 weeks. The 2-week schedule, called interval compression, gave a 5-year event-free survival of 73% versus 65%. Toxicity did not rise. At 10 years, both event-free and overall survival stayed better.

EE2012 ran in ten countries from 2014 to 2019 and enrolled 640 patients. It compared the European VIDE regimen with interval-compressed VDC/IE. Three-year event-free survival was 61% for VIDE and 67% for VDC/IE, with an adjusted hazard ratio of 0.71. The investigators concluded VDC/IE was more effective, less toxic, and shorter.

Surgery is generally preferred when a tumor can be removed. NCI is careful to note that this preference has never been tested in a randomized trial, and that the apparent advantage may reflect selection: smaller, more peripheral tumors were more often operated on. One analysis using propensity scoring found similar event-free survival across surgery alone, radiation alone, and both.

Margins matter after surgery. In a St. Jude series of 39 patients, the 8-year local failure rate was 5% with negative margins and 17% with positive margins.

So does how much tumor is left alive in the specimen. In a French study, event-free survival was 75% when less than 5% of the tumor was still viable, 48% at 5% to 30%, and 20% above 30%.

When surgery is not done, radiation is generally given in fractions totaling about 55.8 Gy to the tumor volume measured before chemotherapy.

For localized disease on the current COG regimen, NCI reports a 5-year event-free survival of 73% and a 5-year overall survival of 88%. Across the years 1975 to 2020, 5-year survival rose from 59% to 80% to 85% for children under 15, and from 20% to 69% for teens aged 15 to 19.

Metastatic disease is harder. Six-year event-free survival is about 28% and overall survival about 30%. Lung or pleural spread alone does better, near 40% at 6 years with bilateral lung radiation. Bone or bone marrow spread runs near 28% at 4 years, and combined lung plus bone or marrow spread near 14%.

Back pain together with new leg weakness, numbness, or trouble controlling urine or stool can mean the spinal cord is being compressed. That combination is an emergency. The nearest emergency department, or 911, is the right call, because fast treatment protects movement and nerve function.

A temperature of 100.4°F (38°C) or higher during chemotherapy is the other emergency. Chemotherapy for Ewing sarcoma drops the white cells that fight infection, and the CDC says a fever at that point can be life-threatening and needs care straight away. Do not wait for a routine appointment: ring the 24-hour oncology number you were given, or go to an emergency department.

Our page on osteosarcoma covers the other main bone cancer of this age group.

• National Cancer Institute, Ewing Sarcoma Treatment (PDQ) - Health Professional Version, updated November 27, 2024, accessed August 6, 2026
• National Cancer Institute, Ewing Sarcoma Treatment (PDQ) - Patient Version, accessed August 6, 2026
• Centers for Disease Control and Prevention, Fever and Cancer Treatment, accessed August 13, 2026