Osteosarcoma: Causes, Symptoms, Diagnosis and Treatment — Overview, Diagnosis & Treatment Options | MyMedicPlus

Osteosarcoma is the most common primary malignant bone tumor, accounting for approximately 20% of all primary bone malignancies and roughly 3-5% of childhood cancers. It arises from osteoblastic mesenchymal cells that produce malignant osteoid (immature bone matrix). The disease has a bimodal age distribution: the most common peak affects adolescents aged 10-20 during the rapid skeletal growth phase of puberty, and a second smaller peak occurs in adults over 60, typically in the setting of Paget's disease of bone, prior irradiation, or bone infarction. Approximately 3,500 new cases are diagnosed annually in the United States. Osteosarcoma most frequently arises in the metaphyses of long bones — particularly the distal femur (around the knee, accounting for approximately 40% of cases), proximal tibia, and proximal humerus — corresponding to the regions of most rapid longitudinal bone growth. High-grade conventional osteosarcoma is the most common subtype, though low-grade parosteal and periosteal variants with more favorable biology also occur.

The vast majority of osteosarcomas arise sporadically without a clearly identifiable cause. Rapid bone growth during the pubertal growth spurt is the most consistent biological association, explaining the adolescent peak incidence. Established hereditary risk factors include: Li-Fraumeni syndrome (germline TP53 mutation), which confers approximately 15% lifetime osteosarcoma risk; hereditary retinoblastoma (germline RB1 mutation), which increases risk roughly 500-fold, with the risk further amplified by radiotherapy; Rothmund-Thomson syndrome (RECQL4 mutation); Werner syndrome (WRN mutation); and Bloom syndrome. Secondary osteosarcoma arises in approximately 1% of patients with Paget's disease of bone and as a radiation-induced sarcoma after a latency of typically 5-20 years following therapeutic irradiation. Somatic alterations in TP53 and RB1 are present in most sporadic osteosarcomas, and WNT pathway alterations and genomic complexity (chromothripsis) are additional common molecular features.

The cardinal presenting symptom is localized bone pain that is often initially intermittent and attributed to exercise-related muscle strain or growing pains — a common and important cause of diagnostic delay in adolescents. The pain characteristically worsens at night and with physical activity. A palpable, firm soft tissue mass overlying the affected bone becomes apparent as the tumor grows through the cortex into the surrounding soft tissues. Swelling and warmth over the affected region may mimic inflammatory or infectious processes. Joint movement may be restricted if the tumor is adjacent to a joint. Pathological fracture through the tumor is an uncommon but recognized presentation in advanced or low-grade lesions. Pulmonary symptoms (cough, dyspnea) may indicate metastatic lung disease. Constitutional symptoms such as fever, weight loss, and fatigue are uncommon in localized disease.

Plain radiographs of the affected bone typically reveal the classic sunburst periosteal reaction (spiculated, radially oriented calcified periosteal new bone), Codman's triangle (elevation of the periosteum at the tumor margin), and mixed lytic-sclerotic medullary destruction. MRI with and without contrast is mandatory for defining local tumor extent, skip lesions within the same bone, and neurovascular involvement for surgical planning. CT of the chest is essential for detecting pulmonary metastases (the most common site of distant disease). Whole-body bone scan or PET/CT identifies bone metastases and skip lesions. Core needle biopsy at a specialized center confirms histological diagnosis. Serum alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) are prognostic markers elevated in high-grade disease.

Treatment of high-grade osteosarcoma follows a neoadjuvant chemotherapy — surgery — adjuvant chemotherapy paradigm, which has been established as the standard of care since the 1980s. The standard MAP chemotherapy regimen consists of high-dose methotrexate (12 g/m² with leucovorin rescue), doxorubicin (75 mg/m²), and cisplatin (120 mg/m²), administered over approximately 10 weeks before surgery. Surgical treatment is limb-salvage surgery (endoprosthetic replacement or osteoarticular allograft) in more than 90% of patients; amputation is reserved for cases where wide surgical margins cannot be achieved with limb preservation. Pathological assessment of tumor necrosis in the resected specimen guides adjuvant chemotherapy selection — good responders (greater than 90% necrosis) continue MAP; poor responders may be enrolled in trials evaluating alternative or intensified regimens. Mifamurtide (liposomal muramyl tripeptide, MTP-PE) has been approved in Europe as an adjunct to MAP chemotherapy, with the MSTS/COG trial showing improved overall survival. Pulmonary metastasectomy is performed for resectable lung-only metastatic disease.

No preventive measures are known for sporadic osteosarcoma, which arises from apparently random somatic mutations during rapid bone growth. For individuals with known hereditary predisposition — particularly germline RB1 or TP53 mutations (Li-Fraumeni syndrome) — structured cancer surveillance protocols including periodic bone and whole-body imaging enable earlier detection of osteosarcoma and other malignancies. Patients with hereditary retinoblastoma should avoid radiotherapy to the bone whenever clinically feasible, as radiation substantially amplifies their already elevated risk of radiation-induced secondary bone sarcoma. Patients with Paget's disease of bone — a known risk condition for secondary osteosarcoma — should be monitored for new bone pain or skeletal changes that may indicate malignant transformation. Genetic counseling is recommended for all children and young adults diagnosed with osteosarcoma to assess for hereditary cancer syndromes.

Parents and adolescents should seek prompt medical evaluation when bone pain — particularly around the knee or upper arm — persists for more than two to four weeks, does not respond to simple analgesics, or is present at night. Pain that awakens a child from sleep is especially concerning. A palpable lump over a bone, unexplained swelling of a limb, or warmth and redness over a bony prominence not due to trauma or infection requires urgent assessment. Because osteosarcoma is frequently initially dismissed as a sports injury or growing pains, a second medical opinion from an orthopedic oncologist is appropriate if symptoms persist despite treatment for a presumed benign musculoskeletal condition. Adults over 60 with new-onset bone pain in areas of known Paget's disease, or any rapidly enlarging bone mass, must be evaluated promptly. Any child with known Li-Fraumeni syndrome or hereditary retinoblastoma who develops unexplained bone pain requires urgent bone imaging.

Localized disease treated with MAP chemotherapy and surgery: 5-year survival approximately 60-70%. Metastatic disease at diagnosis: 5-year survival approximately 20%. Histological necrosis rate greater than 90% after neoadjuvant chemotherapy is the strongest prognostic factor. Pulmonary metastasectomy for oligometastatic lung disease can be curative in selected patients. The prognosis for Osteosarcoma: Causes, Symptoms, Diagnosis and Treatment varies depending on severity at diagnosis, the patient's overall health, and how promptly treatment is initiated. With early diagnosis and appropriate management, many patients achieve good outcomes and maintain quality of life. Regular follow-up with healthcare providers is essential to monitor progress, adjust treatment as needed, and detect any complications early. Adherence to prescribed treatments and lifestyle modifications significantly improves long-term prognosis.