A 14-year-old girl from Mumbai has been diagnosed with Ewing sarcoma of the right tibia (stage IIB, 8 cm lesion, no metastases). She has completed 12 weeks of neoadjuvant chemotherapy (doxorubicin, cisplatin, ifosfamide) with good radiological response (>90% tumor necrosis on MRI). What is the most appropriate next step in management?

Explanation

## Management of Ewing Sarcoma After Neoadjuvant Chemotherapy ### Treatment Algorithm ```mermaid flowchart TD A[Ewing Sarcoma Diagnosed]:::outcome --> B[Neoadjuvant Chemotherapy<br/>12 weeks]:::action B --> C{Tumor Response<br/>on MRI?}:::decision C -->|Good response<br/>90% necrosis| D[Wide Surgical Excision<br/>Limb Salvage]:::action C -->|Poor response<br/>< 90% necrosis| E[Consider Alternative Surgery<br/>or Amputation]:::action D --> F[Adjuvant Chemotherapy<br/>12 weeks]:::action E --> F F --> G[Follow-up Surveillance]:::outcome ``` ### Current Status: Good Response to Neoadjuvant Therapy **Key Point:** This patient has achieved >90% tumor necrosis, which is the threshold for good histological response. The next step is **wide surgical excision with limb salvage reconstruction**. ### Standard Treatment Protocol for Ewing Sarcoma | Phase | Duration | Details | |-------|----------|----------| | **Neoadjuvant chemotherapy** | 12 weeks | Doxorubicin, cisplatin, ifosfamide (standard regimen) | | **Surgical resection** | After chemo | Wide excision with limb salvage if feasible; amputation if not | | **Adjuvant chemotherapy** | 12 weeks | Continuation of same regimen | | **Total treatment** | ~6 months | Chemo + surgery + chemo | **High-Yield:** The sequence is **chemotherapy → surgery → chemotherapy**. Surgery is NOT delayed if good response is achieved. Delaying surgery increases risk of local recurrence. ### Why Proceed to Surgery Now? 1. **Good radiological response** (>90% necrosis) predicts good pathological response 2. **Timing is critical** — surgery should occur 2–4 weeks after completing neoadjuvant chemotherapy 3. **Limb salvage is possible** — the tumor has shrunk and is resectable 4. **Delaying surgery increases risk** of local recurrence and metastatic progression **Clinical Pearl:** Histopathological response at surgery (% tumor necrosis) is the strongest prognostic factor. Patients with >90% necrosis have significantly better 5-year survival (~70%) compared to <90% necrosis (~50%). **Warning:** Do NOT continue chemotherapy beyond 12 weeks preoperatively. Prolonged chemotherapy delays surgery and does not improve outcomes; it increases toxicity risk (cardiotoxicity from doxorubicin, nephrotoxicity from cisplatin).