Disease Description (Causes and Symptoms)
- Summary of definition: Osteosarcoma is a malignant bone tumor that arises in bone. It occurs most commonly in children and adolescents and primarily develops in the metaphyseal regions of long bones, especially around the knee (the distal femur and proximal tibia). It is relatively rare among all malignant tumors and occurs somewhat more often in males.
- Causes and pathophysiology: The exact cause is unknown, but genetic predisposition (for example, an increased risk in patients with hereditary retinoblastoma) and previous radiation exposure may be associated with its development. Malignant osteoblasts produce abnormal osteoid, causing local bone destruction, invasion into surrounding soft tissue, and hematogenous metastasis, particularly to the lungs.
- Main symptoms:
- Early stage: Localized bone pain that worsens with activity (often mistaken for exercise-related pain)
- As the disease progresses: Pain that persists even at rest, localized swelling, and a palpable mass
- With metastasis: Shortness of breath and cough (lung metastasis), bone pain due to multiple bone metastases, and other symptoms
- Epidemiology and clinical course: Approximately 60% of cases occur in children and adolescents, about 10% occur in people in their 20s, and some cases in adults occur as secondary osteosarcoma after radiation exposure. Distant metastases are observed in approximately 10–20% of patients at diagnosis.
Treatment Methods
- Diagnostic preparation: X-ray → if suspected, MRI (evaluation of the local extent of the lesion), chest CT (evaluation for lung metastasis), bone scan or PET (confirmation of other bone metastases), and biopsy (essential) for definitive diagnosis.
- Standard treatment (for localized, resectable lesions):
- Systemic (neoadjuvant) chemotherapy → wide excision (limb-sparing surgery whenever possible) → postoperative adjuvant chemotherapy
- Commonly used drugs and regimens: MAP therapy (high-dose methotrexate + doxorubicin (Adriamycin) + cisplatin) is commonly used as standard treatment; if necessary, combination therapy with ifosfamide/etoposide may be used.
- A high tumor necrosis rate after neoadjuvant chemotherapy (for example, 90% or more necrosis) is associated with a good prognosis.
- When resection is impossible or systemic disease is extensive:
- Chemotherapy alone or consideration of a clinical trial
- Radiation therapy generally has limited effectiveness and is used only as an adjunct
- Lung metastases:
- If the lung metastases are within a resectable range, pulmonary resection (metastasectomy) may be performed to prolong survival (a 5-year survival rate of approximately 40% has been reported in resectable cases).
- Surgical options:
- The possibility of limb-sparing surgery (with prosthetic replacement and reconstruction) has increased, and the rate of amputation has decreased. However, amputation is necessary when functional reconstruction is impossible because of nerve or vascular invasion and other factors.
- Management and side effects during and after treatment:
- Acute side effects of chemotherapy: Nausea and vomiting, hair loss, mucositis, diarrhea, and bone marrow suppression (risk of infection and bleeding)
- Long-term side effects: Cardiotoxicity (associated with doxorubicin), nephrotoxicity (associated with cisplatin), reduced fertility (infertility), and the possibility of secondary malignant tumors
- Monitoring: Blood tests, cardiac function (echocardiography), kidney and liver function tests, and infection prevention and treatment
- Rehabilitation and lifestyle management:
- Physical therapy after surgery (functional recovery and gait training), and adaptation to assistive devices and prostheses
- Counseling on fertility preservation (consideration of sperm or egg preservation before chemotherapy)
- Vaccination and infection control (caution regarding immunosuppression during chemotherapy)
Checklist Before an Outpatient Visit (Including Examples of Items to Bring and Questions)
- Recommended items to bring:
- A list of all medications currently being taken (prescription medications, supplements, herbal medicines, etc.)
- Past medical history and records of surgeries and treatments, as well as previous test results (reports and image CDs from previous X-rays/CT/MRI examinations)
- The timing and course of symptoms (onset, characteristics, aggravating factors, and relieving factors of the pain), and a pain diary (pain severity and whether medication was taken)
- Changes in body weight, presence of fever or night sweats, and any activity limitations
- Family history (history of hereditary cancers) and any previous radiation exposure
- Identification documents and insurance documents
- If swelling or skin changes are present, preparing photographs to show the doctor during the outpatient visit may help with diagnosis.
Examples of General Questions to Ask the Doctor
- What is the exact stage of this disease, and what is the prognosis (survival rate)?
- What treatment options are recommended in my case, and what are the advantages, disadvantages, and expected side effects of each?
- What tests will I mainly undergo during chemotherapy, and how often will they be performed?
- How long is the rehabilitation period after treatment, and when can I expect to return to daily activities (such as school or work)?
- What fertility-preservation options are available (sperm or egg storage), and when should they be pursued?
Examples of Disease-Specific Questions
- How is it determined whether limb-sparing surgery is possible? If limb-sparing surgery is not possible, how long does rehabilitation and adaptation to a prosthesis generally take after amputation?
- How is the response to neoadjuvant chemotherapy (the tumor necrosis rate) evaluated before surgery? How might the treatment plan change if the tumor necrosis rate is low?
(Note: Diagnostic and treatment plans and the management of side effects vary according to each patient’s condition and stage of disease, as well as the treatment protocols of the institution. Specific diagnostic and treatment decisions should be discussed with the treating specialist.)