Osteosarcoma is characterised by the production of osteoid or immature bone by malignant cells.19 In practice, tumours are typically classified according to stage (localised versus metastatic) and grade (low or high grade). Osteosarcoma is broadly classified into three histologic subtypes (intermedullary (central), surface, and extraskeletal).6
The following osteosarcoma types have been identified:18
- Small cell
- Giant cell-rich.
- Low-grade central:
- Fibrous dysplasia-like
- Desmoplastic fibroma-like.
- Dedifferentiated parosteal
- High-grade surface.
The most common pathologic subtype is high-grade intramedullary osteosarcoma which is the classic or conventional form comprising nearly 80% of osteosarcoma.6
For practical purposes, individuals are divided between those who present without clinically detectable metastatic disease (localised osteosarcoma), and those who present with clinically detectable metastatic disease (metastatic osteosarcoma).22 Bone metastases are associated with significantly worse survival outcomes compared with metastatic disease confined to the lungs.19
The American Joint Committee on Cancer (AJCC) TNM staging classification system is based on assessment of histological grade, tumour size, presence of regional and/or distant metastases.6 An outline of the TNM staging system for bone cancer is accessible in the NCCN Guidelines Version 1.2015 Bone Cancer.6
Individuals with suspected osteosarcoma should undergo complete staging prior to biopsy. Principles of management related to biopsy for bone cancer include:6
- biopsy diagnosis is necessary prior to any surgical procedure or fixation of the primary site.
- biopsy is optimally performed at a center that will do definitive management
- placement of the biopsy is critical
- biopsy should be core needle or surgical biopsy
- appropriate communication between the surgeon, musculoskeletal radiologist, and bone pathologist is critical
- fresh tissue may be needed for molecular studies and tissue banking
- final pathological evaluation should include assessment of surgical margins and size/dimensions of tumour.
Compare the likely prognosis for people diagnosed with localised osteosarcoma and metastatic osteosarcoma.
Compare the physical symptoms and psychological needs that may be common among people newly diagnosed with:
- localised osteosarcoma
- metastatic osteosarcoma.
Develop an education plan to prepare AYA for a bone biopsy procedure.
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Plain x-rays revealed an active lesion with poorly defined margins and mild periosteal reaction. Soft tissue mass was present.
A diagnostic workup of MRI and bone scan revealed unilateral pulmonary metastases with no distant spread identified.
Full blood picture, ESR (erythrocyte sedimentation rate), Electrolytes, liver function tests, showed no abnormalities. However, alkaline phosphatise and Lactate dehydrogenase (LDH) were elevated.
Biopsy revealed conventional osteosarcoma of the proximal humerus, osteoblastic histological variant - grade 3.
Met with Justin and his parents. Justin presented as a relatively mature young man.
Provided an explanation that he had a type of bone cancer and would need to have some treatment - chemotherapy in hospital for about 10 weeks and then a biopsy to assess response to treatment before going on for surgery and more chemotherapy.
Discussed the option of a multi-centre international clinical trial being conducted through the Children’s Oncology Group (COG) that might be suitable for him. Indicated he would probably receive some high dose methotrexate with leucovorin rescue, doxorubicin and ifosfamide or similar combination.
Side effects of the chemotherapy discussed - alopecia, increased risk of infection, and infertility. Sperm banking discussed. Urgent referral made to the reproductive unit.
Brief surgical discussion covered high probability of limb sparing surgery with wide excision of tumour in humerus. Wedge resection of lung for pulmonary metastases also required. Will discuss in more detail following response to cytotoxic therapy is apparent.
Outline the prognostic and treatment implications of the following findings from Justin's diagnostic testing:
- Poorly defined margins
- Mild periosteal reaction with soft tissue mass
- Unilateral pulmonary metastases
- Elevated LDH and ALP
- Conventional osteosarcoma of the proximal humerus
- Osteoblastic histological variant - grade 3.
At 16 years of age, Justin's parents would be involved in the decision making process for treatment of his disease. Outline the legal rights of a 16-year-old in relation to treatment consent and decision making.
Discuss how the multidisciplinary team (MDT) could assess Justin's preferences for information and involvement in decision making.