What is the treatment for knee bone cancer?

Treatment for Knee Bone Cancer

Knee bone cancer requires combined chemotherapy and surgery at a specialized reference center, with the specific treatment approach determined by tumor type—high-grade osteosarcoma (the most common type around the knee) is treated with neoadjuvant chemotherapy followed by limb-salvage surgery and adjuvant chemotherapy. 1

Initial Management Principles

• All patients with suspected primary bone malignancy must be referred immediately to a specialized sarcoma center or reference network before any intervention, including biopsy. 1 The complexity and rarity of these tumors demands multidisciplinary care including orthopedic oncology, medical oncology, radiology, and pathology expertise. 1

• Patients should avoid weight-bearing on the affected extremity to prevent pathologic fracture while evaluation is completed. 2 If a pathological fracture occurs, internal fixation is contraindicated as it disseminates tumor cells; external splintage is recommended instead. 1

Diagnosis and Staging

Required Baseline Evaluation

• Local imaging: MRI of the entire affected bone including adjacent joints to detect skip lesions 1
• Metastatic workup: Chest CT (high-resolution spiral preferred), bone scintigraphy, and chest radiographs 1
• Laboratory tests: Complete blood count, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), renal function, liver function, electrolytes including magnesium and phosphate 1, 3
• Cardiac and auditory assessment: Baseline echocardiogram or radionuclide ventriculography and audiogram before chemotherapy 1
• Fertility preservation: Sperm banking for males of reproductive age; fertility consultation for females 1

Elevated ALP and LDH levels correlate with adverse outcomes and higher disease burden. 1, 3

Treatment by Tumor Type

High-Grade Osteosarcoma (Most Common Around the Knee)

This is the standard treatment algorithm:

1. Neoadjuvant (preoperative) chemotherapy for 8-12 weeks 1

   • Standard regimens include:
     • MAP protocol: High-dose methotrexate with leucovorin rescue, cisplatin, and doxorubicin 1, 4
     • Cisplatin and doxorubicin 1
     • Four-drug combinations adding ifosfamide 1

2. Surgical resection with wide margins 1

   • Limb-salvage surgery is preferred and achievable in 80-90% of cases around the knee 1
   • Wide surgical margins (complete tumor removal with unviolated cuff of normal tissue) are mandatory as narrower margins increase local recurrence risk 1
   • Total knee arthroplasty with long intramedullary stems is the gold standard reconstruction 5
   • Amputation is reserved for cases where adequate margins cannot be achieved with limb salvage 1

3. Adjuvant (postoperative) chemotherapy 1

   • Good histologic responders (>90% tumor necrosis): Continue same chemotherapy regimen 1
   • Poor histologic responders (<90% tumor necrosis): Consider alternative chemotherapy regimen, though benefit remains unproven 1
   • Total treatment duration: 6-12 months 1

Multimodal treatment increases disease-free survival from 10-20% (surgery alone) to >60%. 1 The extent of histological response to preoperative chemotherapy predicts survival. 1

Low-Grade Osteosarcoma (Parosteal, Low-Grade Central)

• Surgery alone with wide margins 1
• No chemotherapy indicated due to lower metastatic potential 1

Ewing Sarcoma

• Combined chemotherapy and surgery (or radiation if unresectable) 1
• Chemotherapy regimens: VAC/IE (vincristine, doxorubicin, cyclophosphamide alternating with ifosfamide and etoposide) 6
• Treatment duration: 28-49 weeks depending on protocol 1

Chondrosarcoma

• Surgery is primary treatment as these tumors are chemoresistant 6, 7
• Wide surgical resection with adequate margins 7

Critical Surgical Considerations

• Biopsy must be performed at the treating center by the surgeon who will perform definitive surgery 1 Improper biopsy placement can compromise limb salvage and increase local recurrence risk. 1

• Main surgical challenges around the knee: 8, 5

  • Soft tissue coverage after resection (may require local or free flaps)
  • Extensor mechanism preservation or reconstruction
  • Vascular and nerve preservation

• Radiation therapy has limited role in extremity osteosarcoma and is reserved for unresectable tumors or axial locations 1

Surveillance After Treatment

Follow-up schedule: 1, 6

• Every 3 months for 2 years
• Every 4-6 months for years 3-5
• Every 6-12 months for years 5-10
• Annually after 10 years (especially pediatric patients due to long-term toxicity concerns)

Each visit should include: 1, 6

• Physical examination
• Chest imaging (radiograph or CT)
• Plain radiograph of the affected extremity
• Functional assessment

Prognostic Factors

Adverse prognostic indicators: 1

• Detectable metastases at diagnosis (most important)
• Axial or proximal extremity location
• Large tumor size
• Elevated serum ALP or LDH
• Older age
• Poor histologic response to chemotherapy (<90% necrosis)

Patients with localized disease have 60-80% survival rates, while those with metastatic disease have 20-30% five-year survival. 1, 7

Common Pitfalls to Avoid

• Never perform internal fixation of a pathologic fracture in suspected bone malignancy—this disseminates tumor cells and increases local recurrence risk 1

• Do not biopsy before completing staging workup to avoid tissue plane contamination 3

• Avoid delayed referral to specialized centers—this negatively impacts outcomes 6

• Monitor for long-term chemotherapy toxicity: cardiac dysfunction (anthracyclines), renal dysfunction, auditory impairment (platinum agents), and secondary malignancies 1, 6