What is the recommended treatment approach for primary bone tumors in orthopaedic oncology?

Treatment Approach for Primary Bone Tumors

Primary bone tumors require immediate referral to a multidisciplinary bone sarcoma team at a specialized center before biopsy, followed by a treatment algorithm combining neoadjuvant chemotherapy (for chemosensitive tumors), wide surgical resection with negative margins, and adjuvant therapy based on tumor type and response. 1, 2

Initial Evaluation and Referral

Age-Based Triage

• Patients <40 years with an aggressive, symptomatic bone lesion should be referred directly to an orthopedic oncologist before any further workup due to significant risk of primary malignant bone tumor 1, 3
• Patients ≥40 years require workup for metastatic disease first, including bone scan, chest x-ray, and CT chest/abdomen/pelvis with contrast, as metastases and myeloma are more common than primary bone tumors in this age group 1

Pre-Biopsy Staging Requirements

Complete staging must occur before biopsy to avoid complications 1:

• Plain radiographs in two planes (always first) 1
• MRI of entire involved bone with contrast for local staging 1
• CT chest with contrast to detect pulmonary metastases 1
• Bone scan or FDG-PET/CT for distant bone metastases 1
• Laboratory studies: CBC, comprehensive metabolic panel with calcium, LDH, and alkaline phosphatase (prognostic value in osteosarcoma and Ewing's sarcoma) 1

Biopsy Principles

Core needle biopsy is now preferred over open biopsy due to lower complication rates (88-96% diagnostic accuracy), reduced tissue contamination, and lower cost, though open biopsy remains acceptable when larger samples are needed for molecular studies 1

Critical Biopsy Requirements

• Must be performed at the center providing definitive treatment 1
• Biopsy tract must be planned with the resecting surgeon to ensure it lies within the planned resection bed 1
• Requires multidisciplinary coordination between orthopedic oncologist, interventional radiologist, and bone pathologist 1
• Fresh frozen tissue should be collected for molecular diagnostics; if decalcification needed, use EDTA instead of methanoic acid 1
• Failure to follow proper biopsy technique leads to adverse outcomes in 19% of cases and unnecessary amputation in 3% of cases 1

Multidisciplinary Team Composition

The core team must include at minimum 1:

• Orthopedic oncologist
• Bone pathologist with expertise in sarcomas
• Medical/pediatric oncologist
• Radiation oncologist
• Musculoskeletal radiologist

Additional specialists as needed: thoracic surgeon, plastic surgeon, interventional radiologist, physiatrist, vascular surgeon, neurosurgeon/spine surgeon 1

Treatment Algorithm by Tumor Type

High-Grade Osteosarcoma

Standard treatment is neoadjuvant chemotherapy → surgery → adjuvant chemotherapy 2, 1

• Chemotherapy regimen: MAP protocol (high-dose methotrexate, doxorubicin, cisplatin) for patients <40 years; doxorubicin-cisplatin for patients ≥40 years or those intolerant of high-dose methotrexate 2
• This multimodal approach increased 5-year survival from 10-20% to over 60% in localized disease 2, 4
• Surgical goal: wide excision with histologically negative margins (R0 resection) 2
• 90-95% of patients can be treated with limb-sparing resection rather than amputation 4, 5

Ewing's Sarcoma

Treatment consists of compressed VDC/IE chemotherapy → local control (surgery ± radiation) → adjuvant chemotherapy 3, 1

• Chemotherapy: Vincristine, doxorubicin, cyclophosphamide alternating with ifosfamide and etoposide (compressed schedule preferred for medically fit patients) 3
• Local control: Wide surgical excision when feasible; radiation therapy if complete surgical excision impossible 2, 3
• Postoperative radiation indications: Positive margins, poor chemotherapy response, large tumors in high-risk anatomic areas 3
• Multimodal treatment achieves 5-year survival of nearly 80% in localized disease and 20-40% in metastatic disease 3
• Total treatment duration: 28-49 weeks depending on protocol 1

Chondrosarcoma

Primarily surgical management, as most subtypes are chemoresistant and radioresistant 3

• Wide surgical resection with negative margins is the standard treatment 2, 3
• Chemotherapy and radiation have limited roles except in specific subtypes 3

Surgical Principles

Margin Requirements

• Wide excision with histologically negative surgical margins is mandatory to optimize local tumor control 1, 2
• Narrower margins significantly increase local recurrence risk 2
• The biopsy tract must be excised en bloc with the tumor specimen 1

Limb-Sparing vs. Amputation

• Limb-sparing resection is preferred when reasonable functional expectations can be achieved 1, 5
• No survival difference exists between amputation and adequately performed limb-sparing procedures 5
• Amputation remains appropriate in selected cases where adequate margins cannot be achieved with limb preservation 1, 5

Reconstruction Options

Available techniques include allografts, megaprostheses, and vascularized autografts, with a trend toward more prosthetic reconstructions due to early allograft complications 6

Radiation Therapy Considerations

• Postoperative radiation may reduce local recurrence risk in radiosensitive tumors (particularly Ewing's sarcoma) 2
• Consider for close or positive margins in Ewing's sarcoma 1
• Definitive radiation used when surgery is not feasible 1

Critical Pitfalls to Avoid

Biopsy Complications

• Inappropriate biopsy placement or technique alters treatment plans in 19% of cases 1
• Biopsy at non-specialized centers increases risk of tissue contamination and suboptimal surgical planning 1
• Tumor seeding along biopsy tract occurs if tract not excised with specimen 1

Timing Issues

• Pathologic fracture before treatment increases risk of tumor cell dissemination and local recurrence 1
• Patients should avoid weight-bearing on affected extremity during evaluation 7
• Interval required between surgery and systemic treatment (especially anti-VEGF therapy) to prevent wound complications 1

Fertility Preservation

• Fertility consultation must be offered before initiating cytotoxic chemotherapy in patients of childbearing potential 1
• This discussion should occur before treatment begins, not after 1

Surveillance Protocol

High-Grade Tumors Follow-Up Schedule 2, 3

• Years 1-2: Every 3 months (physical exam, local imaging, chest imaging)
• Years 3-5: Every 6 months
• Years 5-10: Every 6-12 months
• Beyond 10 years: Every 0.5-2 years

Long-Term Monitoring

• Life-long surveillance recommended for late effects of surgery, radiation, and chemotherapy 1
• Cardiac function monitoring essential as deterioration can occur decades after anthracycline treatment 3
• Monitor for secondary malignancies, which may be radiation-related or independent 3
• Survivorship prescription should be provided to schedule multidisciplinary follow-up 1