Ewing’s Sarcoma: Causes

Pathogenesis (disease development)

Ewing sarcoma is one of the osteomyelogenous tumors, meaning that it arises from the bone marrow space from mesenchymal stem cells (immature/undifferentiated tissue cells). It is small-, blue-, and round-celled and highly malignant (highly aggressive; malignancy grade 3 or 4). Ewing’s sarcoma consists almost entirely of tumor cells that replace destroyed bone (osteolytic).

Ewing sarcoma tumor cells have characteristic chromosomal alterations: balanced translocations involving the EWS gene (Ewing sarcoma gene) on chromosome 22. These gene defects cause a healthy cell to become a tumor cell. The most common translocation types are:

  • Translocation t(11;22)(q24;q12)
  • Translocation t(21;22)(q22;q12)
  • Translocation t(7;22)(p22;q12)

Etiology (causes)

The exact causes of primary Ewing sarcoma are still unclear. Familial clustering and environmental influences do not appear to play a role.

Biographic causes

  • Ethnicity-Caucasians (Caucasians) are more commonly affected by Ewing sarcoma, Asians rarely, and African Americans almost never.

Other causes

  • Radioactive exposure
  • X-rays
  • Tumor therapies – Ewing’s sarcoma is more common in people who have undergone chemotherapy and/or radiatio (radiation therapy) in childhood for another tumor disease. The aggressive tumor therapies alter the genome (genetic material) of the osteoblasts.

Guideline

  1. S1 guideline: Ewing sarcomas of childhood and adolescence. (AWMF register number: 025-006), June 2014 long version.