(ChemotherapyAdvisor) –  Patients diagnosed with Ewing sarcoma after age 39 years have significantly higher risks of extra-skeletal tumors and metastatic disease, and poorer 5-year survival rates, than patients diagnosed at younger ages, according to a retrospective cohort study published online in Cancer Epidemiology

“Patients ≥ 40 years at diagnosis with EWS are more likely to have extra-skeletal tumors, metastatic disease, and axial primary tumors, suggesting a difference in tumor biology” compared to younger patients’ EWS,” reported lead author Erin E. Karski, MD, at the UC San Francisco School of Medicine’s Department of Pediatrics, and coauthors.

EWS incidence peaks in adolescence and has been little-studied among patients age ≥ 40 years.

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The authors analyzed US Surveillance Epidemiology and End Results (SEER) cancer data for 2,780 EWS patients, of whom 383 had been diagnosed after age 39 years. Competing risks analysis, χ2 tests, log-rank tests and Cox multivariate analyses were performed to compare EWS characteristics among these patients with those seen among patients diagnosed at younger ages.

“Patients  ≥ 40 years of age were more likely to have extra-skeletal tumors (66.1% vs. 31.7%;P<0.001), axial tumors (64.0% vs. 57.2%; P=0.01), and metastatic disease at diagnosis (35.5% vs. 30.0%;P=0.04) compared to younger patients,” the authors reported.

The median 5-year survival rate for patients age ≥ 40 years at diagnosis was 40.6%, compared to 54.3% among younger patients (P<0.0001). Poorer survival rates among EWS patients diagnosed after age  ≥ 40 years was confirmed using Cox multivariate models that included the disease characteristics identified as significantly different between younger and older EWS patients (HR = 2.04;95% CI, 1.63-2.54;P<0.0001). Details of treatment were not available for inclusion in statistical analyses.

“Independent of differences in these characteristics, older patients also have a lower survival rate,” the authors concluded.