How Bone Cancer Develops

Bone cancer starts when cells in the bone begin to grow abnormally and multiply out of control. In most cases, doctors do not know exactly why this happens. The cancer cells can originate in the bone itself (called primary bone cancer) or spread to the bone from cancer that started elsewhere in the body (called secondary bone cancer). This article focuses on primary bone cancer, which is much less common than cancer that spreads to bone.

Unlike some cancers linked to smoking or sun exposure, bone cancer does not have one clear cause that applies to everyone. Instead, researchers have identified several factors that may increase the risk, though having a risk factor does not mean a person will develop the disease.

Key Takeaways

  • Most bone cancers have no identifiable cause, and doctors cannot predict who will develop them based on lifestyle choices alone.
  • Certain genetic conditions, such as hereditary retinoblastoma and Li-Fraumeni syndrome, significantly raise the risk of bone cancer.
  • Radiation exposure—whether from cancer treatment, medical imaging, or accidents—is a known risk factor that can increase bone cancer risk years later.
  • Bone cancer occurs most often in teenagers and young adults during periods of rapid bone growth, suggesting growth rate may play a role.
  • Paget's disease of bone, a condition affecting how bone is broken down and rebuilt, increases the risk in older adults.

Genetic Conditions That Raise Risk

Some people inherit genetic mutations that make bone cancer more likely. The most well-studied example is hereditary retinoblastoma, a condition caused by a mutation in the RB1 gene. People with this mutation have a significantly higher chance of developing bone cancer, particularly osteosarcoma (the most common type of primary bone cancer). This risk remains elevated throughout life.

Li-Fraumeni syndrome is another inherited condition that increases bone cancer risk. It results from a mutation in the TP53 gene and raises the risk for several types of cancer, including bone cancer. Families with Li-Fraumeni syndrome often have multiple members diagnosed with cancer at younger ages than typical.

Other rare genetic syndromes, such as Rothmund-Thomson syndrome and Werner syndrome, also carry an increased bone cancer risk. If bone cancer runs in your family or you have been diagnosed with one of these genetic conditions, talking with a genetic counselor can help clarify your personal risk.

Radiation Exposure as a Risk Factor

Radiation is one of the few environmental factors clearly linked to bone cancer development. This includes radiation from cancer treatment—for example, a person treated with radiation therapy for another cancer may develop bone cancer in or near the treated area years or even decades later. The risk is higher with higher radiation doses and is greatest in children, whose cells divide more rapidly.

Medical imaging that uses radiation, such as multiple CT scans or X-rays, may also contribute to risk if exposure is repeated over time, though the risk from a single imaging study is very small. Accidental radiation exposure, such as from nuclear accidents, is a less common but documented risk factor.

The time between radiation exposure and bone cancer diagnosis can be long—sometimes 10 to 20 years or more. This delay makes it difficult to prove radiation caused a specific case, but the pattern is clear in population studies.

Age and Rapid Bone Growth

Bone cancer occurs most frequently in teenagers and young adults, particularly during the teenage years when bones grow fastest. Osteosarcoma, the most common type, typically appears in the long bones of the legs and arms during adolescence. This timing suggests that rapid bone growth itself may be a factor, though the exact mechanism is not fully understood.

The second peak in bone cancer incidence occurs in older adults, usually in people with Paget's disease (described below). The rarity of bone cancer in middle-aged adults, when bone growth has slowed, supports the idea that growth rate matters.

Paget's Disease of Bone

Paget's disease of bone is a condition in which bone is broken down and rebuilt abnormally, leading to weakened, deformed bones. People with Paget's disease have a higher risk of developing bone cancer, particularly osteosarcoma, usually in areas where the disease is most active. This risk increases with age and with the duration and severity of the disease.

Paget's disease itself is not cancer, but the abnormal bone remodeling creates an environment where cancer cells may develop more easily. The risk remains relatively low even in people with Paget's disease, but it is higher than in the general population.

Factors That Do Not Cause Bone Cancer

Several things that cause other cancers do not appear to cause bone cancer. Smoking, alcohol use, and diet have not been shown to increase bone cancer risk. Injuries to the bone do not cause cancer, though a fracture may make an existing cancer easier to detect because it brings a person to the doctor.

Occupational exposures linked to other cancers, such as asbestos, have not been established as bone cancer risk factors. Being overweight or sedentary does not raise bone cancer risk. This is one reason bone cancer is so difficult to prevent—there are no clear lifestyle changes that reduce the risk for most people.

What Happens When Cells Become Cancerous

Bone cancer begins when a single cell in the bone acquires mutations that cause it to divide uncontrollably. These mutations can affect genes that normally tell cells when to stop dividing or when to die. Once a cell becomes cancerous, it divides repeatedly, forming a tumor. The tumor can grow into surrounding bone and soft tissue, and cancer cells can break away and spread to other parts of the body, most commonly the lungs.

The specific mutations that cause bone cancer vary from person to person and are often not inherited—they occur randomly in a single cell during that person's lifetime. This is why most people with bone cancer have no family history of the disease and no known risk factors.

Frequently Asked Questions

Can bone cancer be prevented?

There is no proven way to prevent most bone cancers because the causes are not fully understood and are often not related to lifestyle. If you have a genetic condition that raises risk, such as hereditary retinoblastoma, genetic counseling and screening may help catch cancer early. Minimizing unnecessary radiation exposure is sensible but does not eliminate risk.

Is bone cancer hereditary?

Most bone cancer is not hereditary. However, certain inherited genetic mutations, such as those in the RB1 gene (hereditary retinoblastoma) or TP53 gene (Li-Fraumeni syndrome), do increase risk. If multiple family members have had bone cancer or related cancers, genetic testing may be recommended.

Does an old bone injury cause cancer later?

No. Bone injuries and fractures do not cause cancer. However, a fracture may lead someone to get an X-ray that reveals an existing tumor, making it seem like the injury caused the cancer when it did not.

Why do teenagers get bone cancer more often than adults?

Bone cancer occurs most often during the teenage years when bones are growing rapidly. The reason rapid growth increases risk is not completely understood, but the pattern is consistent. Growth-related factors in bone cells may make them more vulnerable to the mutations that lead to cancer.

If I had radiation therapy as a child, will I definitely get bone cancer?

No. Radiation therapy increases the risk of bone cancer, but most people who receive radiation therapy do not develop bone cancer. The risk depends on the dose, the area treated, and the person's age at treatment. Your doctor can discuss your individual risk based on your treatment history.