Adjuvant Therapies

Introduction - Adjuvant Aces

• Adjuvant therapy: Additional cancer treatment given after the primary treatment (usually surgery) to target residual microscopic disease.
• Core Aims:
  • Eradicate micrometastases.
  • Improve local tumour control.
  • Reduce recurrence risk (local & systemic).
  • Enhance overall survival (OS) & disease-free survival (DFS).
• Key Modalities: Chemotherapy, Radiotherapy.
• Crucial for high-grade sarcomas (e.g., Osteosarcoma, Ewing's sarcoma).

⭐ For osteosarcoma, multi-agent adjuvant chemotherapy improves 5-year survival from <20% to ~65%.

Chemotherapy - Chemo Crusaders

Targets micrometastases. Neoadjuvant: shrinks tumor, assesses response. Adjuvant: eradicates residual disease.

• Osteosarcoma:
  • Regimen: MAP (Methotrexate, Adriamycin/Doxorubicin, Cisplatin)
  • High-dose Methotrexate requires Leucovorin rescue.
• Ewing's Sarcoma:
  • Regimen: VDC/IE (Vincristine, Doxorubicin, Cyclophosphamide alternating with Ifosfamide, Etoposide)
• Key Drugs & Toxicities:
  • Doxorubicin: Cardiotoxicity (max lifetime dose 450-550 mg/m²). 📌 "Ruby Red Heart".
  • Cisplatin: Nephrotoxicity, ototoxicity.
  • Ifosfamide/Cyclophosphamide: Hemorrhagic cystitis (prevent with Mesna).
  • Vincristine: Peripheral neuropathy (dose-limiting).
  • Methotrexate: Myelosuppression, mucositis.

⭐ High-dose methotrexate with leucovorin rescue is a cornerstone in osteosarcoma treatment, significantly improving survival rates by allowing for higher, more effective methotrexate doses while protecting normal cells.

Radiotherapy - Radiation Rangers

• Goal: Achieve local tumor control; used pre-operatively, post-operatively, or definitively for unresectable tumors.
• Indications:
  • Ewing's sarcoma (highly sensitive).
  • Soft Tissue Sarcomas (STS): Especially for close/positive margins post-resection, or large/deep tumors pre-operatively.
  • Metastatic disease: Palliation of pain (e.g., bone metastases).
  • Giant Cell Tumor (aggressive/recurrent).
• Types & Doses:
  • External Beam RT (EBRT): Most common. Curative intent: 50-70 Gy.
  • Intensity Modulated RT (IMRT): Spares normal tissues better.
  • Brachytherapy: Radioactive sources placed directly into/near tumor bed.
  • Palliative RT: e.g., 8 Gy single fraction or 30 Gy in 10 fractions.
• Acute Side Effects: Skin reactions (erythema, desquamation), fatigue, mucositis.
• Chronic Side Effects: Fibrosis, lymphedema, pathological fracture, radiation-induced sarcoma. 📌 Mnemonic: "Fibro Lympho And Pathologic Sarcoma" (FLAPS).

⭐ Ewing's sarcoma is highly radiosensitive and radiotherapy forms a crucial part of its multimodality treatment, often used for definitive local control or after surgery if margins are inadequate. Osteosarcomas are generally considered radioresistant.

Targeted & Biologics - Precision Players

• Targeted Therapy: Exploits specific tumor molecular pathways.
  • TKIs (e.g., Pazopanib): For some sarcomas.
  • mTOR inhibitors (e.g., Everolimus).
  • CDK4/6 inhibitors (e.g., Palbociclib).
• Immunotherapy: Enhances anti-tumor immune response.
  • Checkpoint inhibitors (PD-1/PD-L1): Investigational in some sarcomas.
• Bone-Modifying Agents (BMAs): Vital for bone health & tumor control.
  • Bisphosphonates (e.g., Zoledronic acid): Inhibit osteoclasts; for bone mets, GCT.
  • Denosumab (Anti-RANKL mAb): Suppresses osteoclasts. Key for GCT, bone mets.

    ⭐ Denosumab is pivotal for Giant Cell Tumor (GCT), directly targeting RANKL to curb bone resorption.

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High‑Yield Points - ⚡ Biggest Takeaways

• Neoadjuvant chemotherapy for osteosarcoma & Ewing's sarcoma improves resectability and targets micrometastases.
• Adjuvant chemotherapy (post-op) significantly boosts survival in osteosarcoma & Ewing's sarcoma.
• MAP regimen (Methotrexate, Doxorubicin, Cisplatin) is standard for osteosarcoma.
• VDC/IE regimen (Vincristine, Doxorubicin, Cyclophosphamide alternating with Ifosfamide, Etoposide) is standard for Ewing's sarcoma.
• Radiotherapy is crucial for Ewing's sarcoma (highly radiosensitive) and for local control with positive/close margins.
• Denosumab is effective for unresectable or recurrent Giant Cell Tumors (GCT) of bone.
• Imatinib shows efficacy in chordomas and desmoid tumors with specific molecular targets (e.g., KIT/PDGFRA).