Adjuvant Therapies

Adjuvant Therapies - Therapy Team-Up Time

• Definition: Post-primary treatment (e.g., surgery) targeting residual/microscopic disease.
• Aims: ↓ local & systemic recurrence, ↑ disease-free & overall survival.
• Modalities:
  • Chemotherapy: Systemic; vital for Osteosarcoma, Ewing's Sarcoma.
  • Radiotherapy (RT): Local control; for radio-sensitive tumors (e.g., Ewing's), positive margins, or unresectable tumors.
  • Denosumab: For Giant Cell Tumor (GCT), especially unresectable or recurrent cases.

⭐ Neoadjuvant chemotherapy (given before surgery) is standard for high-grade Osteosarcoma & Ewing's sarcoma, improving resectability and aiding limb salvage surgery outcomes.

Adjuvant Therapies - Chemo's Cancer Crush

• Targets micrometastases; improves event-free & overall survival.
  • Neoadjuvant: Pre-operative; shrinks tumor, allows limb salvage, assesses chemo-sensitivity (histologic necrosis).
  • Adjuvant: Post-operative; eradicates residual cells.
• Key Tumors & Regimens:
  • Osteosarcoma: Highly responsive.
    • 📌 MAP protocol: Methotrexate (high-dose with Leucovorin rescue), Adriamycin (Doxorubicin), Cisplatin.
    • Good histologic response (>90% tumor necrosis) correlates with better prognosis.
  • Ewing's Sarcoma: Very chemosensitive.
    • 📌 VDC/IE protocol: Vincristine, Doxorubicin, Cyclophosphamide alternating with Ifosfamide, Etoposide.
  • Chondrosarcoma & Chordoma: Generally chemoresistant.
• Monitoring: Essential for managing toxicities (e.g., cardiotoxicity with Doxorubicin, nephrotoxicity with Cisplatin).

⭐ For Osteosarcoma, the degree of tumor necrosis following neoadjuvant chemotherapy is a critical prognostic factor; >90% necrosis is associated with a significantly better outcome (Huvos grading).

Adjuvant Therapies - Radiation's Radical Rays

• Mechanism: Ionizing radiation damages DNA, inducing tumor cell death.
• Indications: 📌 Sensitive tumors, Positive margins, Unresectable, Palliative (SPUR)
  • Radiosensitive: Ewing's sarcoma, lymphoma, myeloma.
  • Adjuvant: Post-op for close/positive margins.
  • Definitive: Unresectable tumors.
  • Palliative: Pain (metastases), spinal cord compression.
• Modalities:
  • External Beam RT (EBRT): Most common.
  • Stereotactic Body RT (SBRT): Precise, high dose.
• Sensitivity Spectrum:
  • High: Ewing's (~45-60 Gy), Lymphoma, Myeloma.
  • Moderate: Giant Cell Tumor (GCT), Chordoma (high dose needed).
  • Low/Resistant: Osteosarcoma, Chondrosarcoma (RT mainly palliative/unresectable).
• Complications: Dermatitis, osteonecrosis, pathological fracture, radiation-induced sarcoma (late).

  ⭐ Ewing's sarcoma is highly radiosensitive; RT is a key component of its multimodal treatment, often combined with chemotherapy.

Adjuvant Therapies - Precision Bone Battle

• Denosumab (RANKL Inhibitor)
  • Giant Cell Tumor (GCT): Neoadjuvant, unresectable, recurrent.
  • Action: ↓ osteoclast activation & bone resorption.
  • Dose: 120 mg SC.
• Bisphosphonates (e.g., Zoledronic acid)
  • Osteolytic lesions (Myeloma, Mets).
  • Action: Inhibit osteoclasts, ↓ Skeletal-Related Events (SREs).
• Ablative Therapies
  • Radiofrequency Ablation (RFA): Osteoid osteoma, palliative for small mets.
  • Cryoablation: Alternative local control.
• Bone-Targeted Radiopharmaceuticals
  • Strontium-89 ($^{89}\text{Sr}$), Samarium-153 ($^{153}\text{Sm}$).
  • Use: Painful widespread osteoblastic mets.
• Cementoplasty (Vertebroplasty/Kyphoplasty)
  • PMMA cement for pain relief & stabilization (vertebral).

⭐ Denosumab (anti-RANKL mAb) is key for Giant Cell Tumors (GCT), especially unresectable or for downstaging.

High‑Yield Points - ⚡ Biggest Takeaways

• Neoadjuvant chemotherapy is standard for osteosarcoma (MAP: Methotrexate, Doxorubicin, Cisplatin) and Ewing's sarcoma (VDC/IE).
• Ewing's sarcoma is highly radiosensitive; radiotherapy is a key adjuvant treatment.
• Giant Cell Tumors (GCT) may respond to Denosumab (anti-RANKL), especially if unresectable or metastatic.
• Chondrosarcomas are generally chemoresistant and radioresistant; surgery is mainstay.
• Chordomas require surgery followed by high-dose radiation (e.g., proton beam therapy).
• Key toxicities: Cisplatin (nephrotoxicity, ototoxicity), Doxorubicin (cardiotoxicity), Methotrexate (myelosuppression, mucositis).