Bone cancer has several medical names depending on where it starts and what type of cell becomes cancerous

The most common bone cancers are named after the type of cell they develop from. Osteosarcoma starts in osteoblasts, the cells that build bone. Ewing sarcoma develops in immature bone cells and typically affects younger people. Chondrosarcoma begins in cartilage cells and usually grows more slowly than the other two. These three account for the vast majority of primary bone cancers — meaning cancers that start in bone rather than spreading there from elsewhere.

Less common bone cancers include fibrosarcoma (starting in fibrous tissue), giant cell tumor of bone, and chordoma (which develops in the spine). Doctors also distinguish between primary bone cancer, which originates in bone, and secondary bone cancer, which spreads to bone from cancer that started somewhere else — like lung or breast cancer that has metastasized.

Key Takeaways

  • Osteosarcoma, Ewing sarcoma, and chondrosarcoma are the three most common primary bone cancers, each named for the cell type they develop from.
  • Osteosarcoma typically affects teenagers and young adults, while Ewing sarcoma also occurs in younger people but can develop at any age.
  • Chondrosarcoma usually grows more slowly than osteosarcoma or Ewing sarcoma and tends to occur in older adults.
  • Secondary bone cancer means cancer that started elsewhere and spread to bone, which is more common overall than primary bone cancer.

Osteosarcoma: The most common primary bone cancer

Osteosarcoma accounts for roughly 35 percent of primary bone cancers. It develops from osteoblasts, the cells responsible for building new bone tissue. Most osteosarcomas occur around the knee — in the femur (thighbone) or tibia (shinbone) — though they can develop in any bone. The upper arm bone and pelvis are the next most common sites.

Osteosarcoma typically appears in teenagers and young adults during growth spurts, when bone cells are dividing rapidly. It can occur at any age but is rare in people over 40. The cancer tends to grow quickly and can spread to the lungs if not treated. Pain and swelling around the affected bone are often the first signs.

Ewing sarcoma: Fast-growing cancer in young people

Ewing sarcoma is the second most common primary bone cancer and accounts for roughly 25 percent of cases. It develops in immature bone cells and most often appears in people under 30, with peak incidence in the teenage years. Like osteosarcoma, it frequently occurs around the knee, but it can also develop in the pelvis, upper arm, or lower leg.

Ewing sarcoma grows quickly and often spreads to the lungs or other bones before it is detected. Pain, swelling, and sometimes fever or fatigue are common early symptoms. The cancer is named after James Ewing, the pathologist who first described it in 1921.

Chondrosarcoma: Slower-growing cartilage cancer

Chondrosarcoma develops from chondrocytes, the cells that make up cartilage. It accounts for roughly 25 percent of primary bone cancers and typically grows more slowly than osteosarcoma or Ewing sarcoma. Most chondrosarcomas occur in adults over 40, often in the pelvis, femur, or humerus (upper arm bone).

Because chondrosarcoma grows slowly, it may not cause noticeable symptoms for months or years. Pain or a growing lump are the most common signs. The slower growth rate means some chondrosarcomas are caught at an earlier stage, though they can still spread if left untreated.

Less common bone cancer types

Fibrosarcoma develops from fibrous tissue in bone and is now quite rare, partly because some tumors once classified this way are now recognized as other types. Giant cell tumor of bone is usually benign but can occasionally become malignant. Chordoma is a rare cancer that develops in the spine or base of the skull from remnants of the notochord, a structure present during fetal development.

Adamantinoma (which occurs in the tibia), hemangioendothelioma, and leiomyosarcoma are other rare primary bone cancers. Because these types are uncommon, less research exists on their behavior and treatment compared to osteosarcoma, Ewing sarcoma, and chondrosarcoma.

Primary versus secondary bone cancer

Primary bone cancer starts in bone tissue itself. Secondary bone cancer, also called metastatic bone cancer, occurs when cancer that began elsewhere spreads to bone. Lung cancer, breast cancer, prostate cancer, and kidney cancer commonly metastasize to bone.

Secondary bone cancer is actually more common than primary bone cancer overall. However, when doctors refer to "bone cancer" without qualification, they usually mean primary bone cancer. The treatment approach differs significantly depending on whether the cancer originated in bone or spread there from another site.

How doctors name and stage bone tumors

Doctors use the tumor's location, size, and cell type to name and classify bone cancers. A pathologist examines tissue under a microscope to determine which cells are cancerous, which determines the specific name. Imaging tests like X-rays, MRI, and CT scans show where the tumor is located and how large it is.

Staging describes how far the cancer has spread. Stage 1 means the cancer is small and contained within the bone. Stage 2 means it is larger but still localized. Stage 3 means there are tumors in multiple locations within the same bone or nearby bones. Stage 4 means the cancer has spread to distant sites like the lungs or other bones. The specific stage affects treatment decisions and prognosis.

Frequently Asked Questions

Is bone cancer the same as bone tumors?

No. A bone tumor can be benign (noncancerous) or malignant (cancerous). Benign bone tumors like osteochondromas or giant cell tumors do not spread and usually do not threaten life. Malignant bone tumors are cancers that can spread to other parts of the body. A doctor must examine the tissue to determine whether a bone tumor is benign or malignant.

Can bone cancer spread to other bones?

Yes. Bone cancer can spread to other bones, the lungs, or other organs. This spread is called metastasis. Osteosarcoma and Ewing sarcoma spread relatively quickly if untreated, while chondrosarcoma typically spreads more slowly. Treatment aims to prevent or stop this spread.

What is the difference between osteosarcoma and chondrosarcoma?

Osteosarcoma develops from bone-building cells and grows quickly, usually in teenagers and young adults. Chondrosarcoma develops from cartilage cells and grows slowly, usually in older adults. Osteosarcoma is more aggressive and spreads faster, while chondrosarcoma may take months or years to cause noticeable symptoms.

Why do some bone cancers occur in young people?

Osteosarcoma and Ewing sarcoma most often occur during periods of rapid bone growth, particularly during the teenage growth spurt. Bone cells are dividing quickly at these times, which may increase the chance of a cell mutation that leads to cancer. This does not mean rapid growth causes cancer, only that the risk is higher when cell division is most active.

Can you have bone cancer without knowing it?

Yes, especially with chondrosarcoma, which grows slowly and may not cause pain or visible symptoms for a long time. Some bone cancers are discovered incidentally on imaging done for other reasons. However, most bone cancers eventually cause pain, swelling, or a noticeable lump that prompts a person to seek medical attention.