Definition:
- Malignant small round blue cell tumor of bone or soft tissue, arising from neural crest or primitive mesenchymal cells.
- Part of the Ewing family of tumors (EFT).
Epidemiology
- Peak incidence: adolescents and young adults (10–20 years)
- Slight male predominance
- Common sites: pelvis, femur, humerus, ribs, scapula
- Rare in children <5 or adults >30
Genetics
- t(11;22)(q24;q12) translocation → EWS-FLI1 fusion gene in ~85% of cases
- Fusion drives oncogenesis and is a diagnostic marker
Clinical Features
- Localized pain and swelling
- Pathologic fracture may occur
- Systemic symptoms: fever, fatigue, weight loss (sometimes)
- Metastases: primarily to lungs, bone, and bone marrow
Treatment & Pharmacist Role
1. Multi-modal Therapy
- Neoadjuvant chemotherapy: shrink tumor pre-surgery
- Surgery: limb-sparing resection if feasible
- Radiotherapy: adjuvant or definitive if unresectable
2. Chemotherapy Backbone
- VDC/IE regimen:
- VDC: Vincristine, Doxorubicin, Cyclophosphamide
- IE: Ifosfamide, Etoposide
3. Pharmacist Considerations
- Vincristine: neuropathy (max 2 mg/dose)
- Doxorubicin: cardiotoxicity → monitor cumulative dose
- Cyclophosphamide / Ifosfamide: hemorrhagic cystitis → MESNA + hydration, nephrotoxicity
- Etoposide: myelosuppression, risk of secondary leukemia
- Monitor hematologic toxicity, renal/hepatic function, hydration, antiemetics
High-Yield Pharmacist Pearls
- Multi-agent chemo is intensive, requires supportive care and monitoring
- Radiotherapy often used for unresectable tumors or residual disease
- Prognosis depends on tumor size, site, metastasis, response to chemo
- Long-term: monitor cardiac function, growth, fertility, secondary malignancies