Bone cancer is a malignant growth that develops in bone tissue (primary bone cancer) as opposed to occurring in bone due to spread from another organ (metastatic bone disease).
Primary bone cancers represent distinct histologic types each with different expansion patterns, affected age groups, and therapeutic strategies.
What is Bone Cancer?
Primary bone cancer starts in cells of the bone. Doctors use the term bone sarcoma when referring to primary bone cancers, distinguishing them from far more frequent metastatic bone lesions.
Primary bone cancers occur at ~1 new case per 100,000 individuals in the United States annually (~1 to 3 cases per million worldwide).
Bone cell structure: Osteoblasts (make new bone), Osteoclasts (break down extra bone framework), and Osteocytes (maintain bone structure). Marrow spaces contain blood-forming stem cells.
Types of Primary Bone Cancer
• Chondrosarcoma: Most common primary bone cancer type, developing from cartilage cells (most often in adults aged 30–60).
• Osteosarcoma: Second most common, developing from bone-forming cells. Common in children, teenagers, young adults, and older adults (70s–80s).
• Ewing Sarcoma: Affects children and adolescents, developing in bone or soft tissues (muscle, fat, blood vessels).
• Round Cell Sarcoma: Related to Ewing sarcoma and defined by specific gene mutations.
• Rarer Types: Undifferentiated pleomorphic sarcoma of bone, Fibrosarcoma, Leiomyosarcoma, Spindle cell sarcoma, and Chordoma (along spine or skull base).
Locations & TNM Staging
Common locations: Osteosarcoma (metaphysis of long bones like distal femur, proximal tibia/humerus); Ewing sarcoma (shaft of long bones, pelvis, ribs); Chondrosarcoma (pelvis, femur, humerus); Chordoma (spine or skull base).
Staging (TNM & Grades G1-G3): Stage 1A/1B (localized low grade) to Stage 4A/4B (distant metastasis to lungs, liver, brain, or other bones).
Symptoms & Risk Factors
Common symptoms: Persistent bone pain (worse at night/rest), visible swelling or lump, limping/stiffness, pathological fractures from minor injury, fever, sweats, and weight loss.
Risk factors: Genetic inherited syndromes like Li-Fraumeni syndrome (TP53 mutation) and retinoblastoma syndrome (RB1 mutation); prior radiation therapy to bones; Paget's disease of bone.
Diagnosis & Multidisciplinary Treatment
Diagnosis: X-rays (reveals bone destruction), MRI (tumor size & soft tissue extent), CT scan (lung metastases), PET-CT (bone spread), and Biopsy (determines tumor grade/type).
Treatment: Limb-sparing surgery with reconstruction (prosthesis/bone graft), Chemotherapy (pre-op to shrink tumor & post-op), Radiotherapy, Targeted therapies (denosumab), Bisphosphonates, RFA, and palliative care.