What is the initial workup for a patient suspected of having osteosarcoma (bone cancer)?

Initial Workup for Suspected Osteosarcoma

The initial workup for a patient suspected of having osteosarcoma should include imaging of the primary site (contrast-enhanced MRI with or without CT), chest imaging including chest CT, and head-to-toe FDG-PET/CT and/or bone scan, along with laboratory tests for ALP and LDH levels. 1

Imaging Studies

Primary Site Evaluation

1. Plain Radiographs

   • First imaging study to be performed
   • Key findings: cortical destruction, irregular reactive bone formation, "sunburst" appearance, Codman's triangle, and new bone formation in soft tissues 2
   • Helps establish initial suspicion of osteosarcoma

2. MRI with Contrast

   • Most important imaging modality for local staging
   • Provides excellent soft tissue contrast
   • Defines:
     • Extent of lesion within bone and soft tissues
     • Presence of "skip" metastases
     • Anatomic relationships with surrounding structures
     • Involvement of neurovascular structures
     • Joint involvement 1

3. CT Scan (optional)

   • May be used as an adjunct to conventional radiography
   • Better evaluation of bone matrix and cortical destruction 3

Metastatic Workup

1. Chest CT

   • Mandatory for all patients
   • Lung is the most common site of metastasis 1

2. Bone Scan

   • Detects additional synchronous bone lesions
   • Identifies osseous metastases 1

3. FDG-PET/CT

   • Head-to-toe evaluation
   • Detects both bone and soft tissue metastases
   • Helps in overall staging 1, 3

Laboratory Studies

1. Alkaline Phosphatase (ALP)

   • Frequently elevated in osteosarcoma
   • Prognostic value 1

2. Lactate Dehydrogenase (LDH)

   • Significantly higher in patients with metastatic disease
   • Important prognostic marker 1

Biopsy

• Required for definitive diagnosis
• Reveals grade of tumor
• Should be planned by the surgeon who will perform the definitive surgery
• Biopsy tract must be considered contaminated and should be resected during definitive surgery 2

Genetic Considerations

• Consider genetic consultation and testing for patients with:
  • Family history of bone sarcomas
  • Personal history of other cancers
• Genetic syndromes associated with osteosarcoma:
  • Li-Fraumeni syndrome
  • Hereditary retinoblastoma
  • Rothmund-Thomson syndrome type 2
  • Bloom syndrome
  • Werner syndrome
  • RAPADILINO syndrome
  • Diamond-Blackfan anemia 1

Fertility Preservation Discussion

• Important for children and adolescent/young adult patients
• Should be discussed before starting treatment
• Fertility preservation methods should be offered when appropriate 1

Common Pitfalls to Avoid

1. Delayed Diagnosis

   • Pain may be intermittent initially and confused with growing pains or musculoskeletal injury
   • Maintain high index of suspicion in adolescents with persistent bone pain

2. Inadequate Imaging

   • Relying solely on plain radiographs
   • Not performing complete metastatic workup

3. Improper Biopsy

   • Poorly planned biopsy can compromise limb-salvage surgery
   • Biopsy should be performed at the treating center by the surgical team

4. Missing Skip Lesions

   • Failure to detect skip metastases can lead to inadequate surgical planning
   • MRI of the entire bone is essential

Prognostic Factors to Assess

• Tumor site and size
• Patient age and sex
• Presence and location of metastases
• Surgical margins achievability
• Response to neoadjuvant chemotherapy 1

The comprehensive initial workup is crucial for accurate staging and treatment planning, which directly impacts patient survival. The 5-year survival rate for osteosarcoma is approximately 68% overall, but outcomes are significantly better with early detection and appropriate management 4.