Osteosarcoma Diagnosis and Management

Epidemiology and Demographics

Osteosarcoma is the second most frequent primary bone cancer, comprising 4% of solid cancers in children and 3% in teenagers and young adults, with an incidence of 0.2-0.3 per 100,000 per year overall, but rises to 0.8-1.1 per 100,000 per year in adolescents aged 15-19 years 1, 3, 4
The disease has a bimodal age distribution, with the first peak in teenagers and young adults, and the second peak in the seventh and eighth decades, and is more common in males, with a male-to-female ratio of 1.4:1 1, 2, 3, 4
Osteosarcoma is slightly more common in Black patients, and survival rates are higher in younger patients 1

Conventional high-grade osteosarcoma accounts for 80-90% of cases, with subtypes including osteoblastic, chondroblastic, and fibroblastic variants, and other high-grade variants include telangiectatic, small cell, and high-grade surface osteosarcoma 2, 3
Low-grade variants include low-grade central and parosteal osteosarcoma, and periosteal osteosarcoma is an intermediate-grade variant 1, 2, 3

Previous radiation therapy, Paget's disease of bone, and germline genetic abnormalities, such as Li-Fraumeni syndrome, Werner syndrome, Rothmund-Thomson syndrome, Bloom syndrome, and familial retinoblastoma, are associated with an increased risk of osteosarcoma 1, 2, 3, 4

Pain is the cardinal symptom, and night pain is a critical "red flag" requiring immediate investigation, with pain often occurring at rest or during the night, and localized swelling following pain and indicating tumor progression through cortex 2, 6, 7
Limitations of joint movement develop as disease progresses, and the average duration of symptoms before presentation is 3 months 2, 6

Osteosarcoma usually arises in the metaphysis of extremity long bones, most commonly around the knee, with the distal femur and proximal tibia being the most common sites 1, 2, 3, 6

Osteosarcoma spreads hematogenously, with the lung being the most common metastatic site 7

Urgent plain radiographs in two planes are the mandatory first investigation, with MRI being essential for local staging and must be completed before biopsy 2, 4, 6
CT chest for pulmonary metastases, and bone scintigraphy or PET/CT for detecting distant metastases are also recommended 4

The American Society of Clinical Oncology recommends that patients with suspected osteosarcoma be referred to a specialized bone sarcoma center before biopsy, as inappropriate biopsy techniques can irrevocably compromise chances for limb salvage or even cure 2, 5, 6
The National Comprehensive Cancer Network recommends that tumor site and size, patient age at diagnosis, presence and location of metastases, histologic response to chemotherapy, and type of surgery and surgical margins be considered when determining prognosis 7