TriangleHEALTH PROFESSIONAL · SOURCE READING
Undifferentiated Sarcoma
Source: Childhood Soft Tissue Sarcoma Treatment (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: April 21, 2025 · Captured 2026-09-09.
Selected source text with whitespace normalised. This Triangle page is not an NCI PDQ summary.
Context: Treatment of Tumors of Uncertain Differentiation
From 1972 to 2006, patients with undifferentiated soft tissue sarcoma were eligible for participation in rhabdomyosarcoma trials coordinated by the IRS group and the COG. The rationale was that patients with undifferentiated soft tissue sarcoma had sites of disease and outcomes that were similar to those in patients with alveolar rhabdomyosarcoma. Therapeutic trials for adults with soft tissue sarcoma include patients with undifferentiated soft tissue sarcoma and other histologies, which are treated similarly, using ifosfamide and doxorubicin, and sometimes with other chemotherapy agents, surgery, and radiation therapy.
In the COG ARST0332 (NCT00346164) trial, patients with high-grade undifferentiated sarcoma were treated with an ifosfamide- and doxorubicin-based regimen. Results for the patients with high-grade undifferentiated sarcoma were reported together with all high-grade soft tissue sarcomas in the trial. The estimated 5-year EFS rate was 64% and the OS rate was 77% for sarcomas classified as high grade by the Fédération Nationale des Centres de Lutte Contre Le Cancer (FNCLC).[5][Level of evidence C1]
Source links and citations
In a report of 32 patients with undifferentiated soft tissue sarcomas who were enrolled on the ARST0332 (NCT00346164) trial, the median age at enrollment was 13.6 years, and two-thirds of the patients were male. The most common primary sites were the paraspinal region and extremities. Five patients presented with metastatic disease.[148]
Source links and citations
The 5-year EFS rate was 71%, and the OS rate was 83%.
Of the nine children with low-risk disease (localized low-grade resected disease or localized high-grade disease <5 cm resected with negative margins) who were treated with surgery or radiation therapy only, the 5-year EFS rate was 65% and the OS rate was 100%, suggesting that patients with low-risk disease can be salvaged if the disease recurs.
The remaining 23 patients had either intermediate-risk disease (resected high-grade tumor >5 cm, unresected high-grade tumor >5 cm) or high-risk disease (metastasis to lymph nodes or distant sites) and were treated with chemoradiation therapy and delayed surgery when feasible. The 5-year EFS rate was 73%, and the OS estimate was 77%.
Copy number aberrations were common, most frequently involving loss of 1p (25%), gain of 1q (25%), gain of chromosome 8 (25%), and gain of chromosome 2 (16%). These alterations were more commonly seen in patients with intermediate-risk or high-risk tumors, and there was a strong association between loss of chromosome 1p or gain of chromosome 1q and inferior clinical outcomes. Co-occurrence of 1q gain and 1p loss was associated with a particularly poor clinical outcome (5-year EFS and OS rates of 20%). Next-generation sequencing identified oncogenic fusions in eight of ten tumor samples, which included BCOR and CIC rearrangements, as well as COL1A1::PDGFB, KIAA1549::BRAF, and SAMD5::SASH1 gene fusions.
Studies cited in this source section
Source citation is not a determination that a study applies to you.
Publication references
Read the original reference and check its publication notices.
Preserved source evidence · Not medical advice