A 14-year-old girl with Ewing sarcoma of the right femur is being counseled about her disease and treatment options. Her parents ask about prognostic factors and complications. All of the following are associated with POOR prognosis in Ewing sarcoma EXCEPT:

Explanation

## Prognostic Factors in Ewing Sarcoma **Key Point:** Good response to neoadjuvant chemotherapy (>90% tumor necrosis, i.e., >90% cell death) is a **favorable prognostic indicator**, not a poor prognostic factor. This is one of the strongest predictors of improved survival. ### Prognostic Factors in Ewing Sarcoma | Factor | Prognostic Impact | Notes | |--------|-------------------|-------| | **Tumor size** | Large (>8 cm) = POOR | Larger tumors have higher metastatic potential | | **Metastases at diagnosis** | Present = POOR | Pulmonary mets in 20–25% at diagnosis; dramatically worsens prognosis | | **Tumor location** | Pelvis/proximal femur = POOR | Difficult surgical access, delayed diagnosis, higher recurrence | | **Response to chemo** | >90% necrosis = GOOD | Indicates chemosensitivity; associated with 5-year survival >70% | | **Age** | Younger = GOOD | Patients <10 years may have better outcomes | | **EWS-FLI1 type** | Type 1 fusion = variable | Type 2 may have slightly worse prognosis (controversial) | ### Why This Is the Answer The question asks for the factor that is **NOT** associated with poor prognosis. Good chemotherapy response (>90% necrosis) is a **favorable** prognostic sign, making it the exception among the four options. **High-Yield:** Ewing sarcoma is **chemosensitive**. Tumors showing >90% necrosis after neoadjuvant chemotherapy have significantly better survival (5-year OS ~70–80%) compared to poor responders (<90% necrosis, 5-year OS ~30–40%). **Clinical Pearl:** The standard treatment for localized Ewing sarcoma is **neoadjuvant chemotherapy (doxorubicin, cisplatin, ifosfamide) → surgical resection → adjuvant chemotherapy**. Histological assessment of chemotherapy response guides further management. **Mnemonic: PEST** (Poor prognosis factors in Ewing sarcoma): - **P**elvis or proximal location - **E**xtensive size (>8 cm) - **S**ystemic metastases (especially lungs) - **T**umor unresponsive to chemotherapy (<90% necrosis) [cite:Robbins 10e Ch 26]