Osteosarcoma

January 22, 2026

This page was reviewed under our medical and editorial policy by Lee Cranmer, M.D., Ph.D., professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte.

Osteosarcoma is an aggressive type of bone cancer that accounts for around 1,000 new cancer diagnoses every year. It affects people of all ages. Many cases occur in children, teens and young adults. A second group particularly affected are those between 50 and 70 years old.

What Is Osteosarcoma?

Osteosarcoma is a form of cancer. It develops from the cells that produce the bone. When they become cancerous, they grow out of control and form tumors. Because osteosarcomas develop from the cells that produce bone, they often produce bone within the tumor. However, this bone may form in places where bones do not typically occur, and does not provide support like standard bones do.

Although it may occur in any bone of the body, osteosarcoma most often starts near the shoulder, knee or hip and may affect the long bones in the arms or legs. Osteosarcoma is an aggressive form of bone cancer that may spread quickly. It tends to spread through the blood. It often spreads to the lungs and may do so very early. For this reason, chemotherapy is important in treating this disease, because chemotherapy may eradicate osteosarcoma from the lung if it is given before tumors may be detected in the lung.

Osteosarcoma vs. Ewing Sarcoma

People with osteosarcoma may experience similar symptoms to those affected by Ewing sarcoma — another form of bone cancer that is also common among children and young adults. However, the two diseases are different in several key ways, as detailed below.

Osteosarcoma: This type of cancer most often starts in bones around the knee and affects people aged between 10 and 30.

Ewing sarcoma: This may start in the long bones of the arm or leg, but is also commonly found in the spine, pelvis or ribs. It tends to affect children and young adults between 10 and 20 years old.

Osteosarcoma and Ewing sarcoma may both cause pain and swelling in the bone. But Ewing sarcoma often comes with other symptoms, such as numbness, fatigue, weight loss or changes in blood cell count. Treatment for these two conditions may also differ depending on the location and stage of sarcoma. Both forms of cancer require the use of chemotherapy, in addition to surgery or radiation therapy, for optimal outcomes.

Causes and Risk Factors

The specific causes of osteosarcoma are not yet fully understood. However, there are certain risk factors that may make it more likely that someone develops this condition, as listed below.

Age: Osteosarcoma is most common in kids and young adults aged 10 to 30. People 50 to 70 years old are also at higher risk.

Exposure to radiation therapy: Being exposed to radiation may increase the risk for developing osteosarcoma. The most common reason for this is receiving radiation many years before for treatment of cancer.

Other bone diseases: Patients with rare bone conditions such as Paget disease of the bone or fibrous dysplasia have a higher risk for developing osteosarcoma.

Inherited genetic mutations: Inherited cancer syndromes, such as retinoblastoma and Li-Fraumeni syndrome, have been linked to higher rates of osteosarcoma.

Acquired genetic mutations: Osteosarcoma, and almost all forms of cancer, are caused by changes in the DNA or genetic code of cells in the body. As people go through life, they are naturally exposed to substances and radiation in our environment. Thus, cells in the body may develop genetic mutations. Most of these changes have no effect. However, sometimes, the right combination of changes may occur that lead to cancer. For most people with osteosarcoma, the disease develops due to development of such changes, without any clear reason that scientists identify.

Osteosarcoma Symptoms

Because osteosarcoma is an uncommon disease, there is no way to screen people for this disease. There are several common ways in which people come to medical attention and are diagnosed with osteosarcoma. For some people, the diagnosis is “incidental.” This means that they have a medical test, often an X-ray, for another purpose and the disease is identified accidentally. However, most people who develop osteosarcoma experience some of the following signs or symptoms:

• Pain at the site of the tumor, often in an arm or leg bone or around the elbow or knee joint
• Swelling over the top of a bone, sometimes in the form of a lump or hard mass
• A limp or trouble walking, if the tumor is in a leg bone
• Weakened bones, sometimes leading to unexplained (also called “pathologic”) bone fractures. It indicates there was some reason that the bone was weakened. In this case, it is due to a cancer weakening the bone

Tests for Diagnosing

Multiple tests are available to help diagnose osteosarcoma and determine its extent. These tests help patients get the most appropriate treatment for the condition. The most common are listed below.

A physical exam: In an office examination, a doctor examines a patient and discusses his or her symptoms and medical history. In some cases, a bone tumor may be detectable on the outside of the skin during a physical examination.

Imaging tests: X-rays, magnetic resonance imaging (MRI), computed tomography (CT), positron-emission tomography (PET) or bone scans may help locate a tumor, determine its size and extent and provide insight into whether the cancer started in the bone or has spread there from elsewhere. In addition, these tests may help determine whether the cancer has spread to other parts of the body and how fast it is growing.

A biopsy: Ultimately, all cancers are diagnosed by obtaining a sample of the tumor and having a pathologist (a doctor specializing in laboratory assessments) examine the specimen and determine whether it is cancerous. In addition, the pathologist may perform tests that reveal more detailed information about the cancer that may be useful in predicting its behavior and planning treatment.

There are many ways that this type of sample may be obtained. For example, doctors may perform a core needle biopsy, which uses a narrow, hollow needle to remove a sample. Such biopsies are often performed with the aid of imaging tests, such as ultrasound or CT to place the needle in the correct location. In other cases, doctors may recommend that the patient have an operation to obtain a specimen for analysis.

In osteosarcoma and other types of sarcomas, the approach to obtaining a specimen of the cancer is best decided in consultation with bone cancer experts.

Stages

After diagnosing osteosarcoma, doctors determine the cancer’s stage. Cancer stages describe whether cancer has spread, and if so, how far it has spread.

Localized vs. Metastatic Osteosarcoma

The first step in staging osteosarcoma is to find out whether the cancer is localized or metastatic, as detailed below.

Localized osteosarcoma: This means the cancer is confined to the bone where the cancer started. In some cases, it may also affect tissue surrounding the bone, such as cartilage or muscle. Most osteosarcomas are localized when initially diagnosed. However, scientists know based on experience that the disease has often spread to other parts of the body at the time of diagnosis, even if the care team cannot see tumors on imaging studies. This is why chemotherapy is a key component in treatment of this condition.

Metastatic osteosarcoma: This means the cancer has spread beyond the bone where it started to another part of the body. Often, osteosarcoma spreads to the lungs or other bones, but it may spread to any part of the body.

Osteosarcoma may also be described as “resectable,” meaning that all visible cancer may be removed surgically, or “non-resectable,” meaning that it may not be completely removed by surgery.

MSTS Staging System

Staging is the process by which the extent of a cancer is determined. This then allows decisions to be made regarding appropriate treatment. For example, if cancer is identified in only one location within a patient’s body, surgery would often be considered the main treatment in an attempt to cure the patient of that cancer. In contrast, if the cancer has “metastasized,” it is in different parts of the body and surgery may not be useful to treat the condition. In those circumstances, other treatments, such as chemotherapy, may be the primary treatment. Determining the extent or “stage” of the cancer may help guide this decision-making. This is true for osteosarcoma, as it is for other types of cancer.

There are several systems used to stage osteosarcoma. These generally classify patients into lower stages (designated by numbers or letters), which generally reflect more localized disease and higher stages, which reflect disease that has spread to other parts of the body. One such system is that of the Musculoskeletal Tumor Society, referred to as the MSTS staging system. The MSTS system stages osteosarcoma by assessing the following:

Grade (G) of the tumor: This refers to how likely the cancer is to spread. This is based on whether the cancer cells look more like normal cells (grade 1, or low grade) or less like normal cells (grade 2, or high grade) when examined under a microscope

Extent (T) of the tumor: This refers to whether it has remained in the bone it started in or spread to other tissue around the bone.

Whether the tumor has metastasized (M): This indicates if the tumor has spread beyond the bone to affect the lymph nodes or other organs in the body.

Using this information, osteosarcoma may be described as stage 1, 2 or 3, as follows:

• Stage 1 osteosarcoma is localized with low grade tumors
• Stage 2 osteosarcoma is localized with high grade tumors
• Stage 3 osteosarcoma is metastatic, and may be either low or high grade

Note that the highest “stage” in the MSTS system is stage 3. In other systems, this may be referred to as stage 4. In systems which have four stages, stage 3 would still generally be localized disease, although more advanced than stage 1 or 2.

Osteosarcoma Treatment

Treatment for osteosarcoma may involve one or several different therapies. Patients work closely with their treatment team to create an effective treatment plan based on factors including the cancer’s stage and their patient’s overall health and goals for treatment.

Surgery

Surgery is the oldest, and still one of the most important, treatment options for osteosarcoma. Surgery is the main treatment for localized osteosarcoma and may even be used to help those with metastatic osteosarcoma. Cancer surgeons may use open surgery or less invasive options to remove a tumor. Sometimes, this treatment may cure the disease.

Radiation Therapy

Radiation therapy is sometimes used after surgery to target cancer cells that are left in the body. Doctors specializing in the use of radiation to treat cancer are called radiation oncologists. Most often, radiation will be generated by a machine and aimed very precisely either at cancerous tumors or areas where cancer cells may still be in the body. This might be the case if a cancerous tumor was located in a place where complete surgical removal is difficult and the surgeon feels that there is a high chance that the disease was not successfully removed.

Chemotherapy

Chemotherapy medicines are intended to attack cancer cells, in much the same way that antibiotics are intended to treat bacteria that cause infections. In fact, many chemotherapy medicines were originally developed as antibiotics, but were found to be more useful as anti-cancer drugs.

The treatment of osteosarcoma has been revolutionized by chemotherapy. Before the availability of chemotherapy for this disease in the early 1970s, the disease was often fatal. While cancer could be removed by surgery, the majority of patients already had metastatic disease in their bodies that could not be seen at the time of surgery.

It was found that chemotherapy, given at the time of the initial diagnosis, could eradicate the tumor cells that had spread in the body, if it was given before those cells turned into visible tumors. Since that time, chemotherapy regimens have been investigated and improved. At the present time, approximately 50% to 65% of all patients with osteosarcoma are ultimately cured of their conditions. While chemotherapy cannot do this alone, it would not have been possible without chemotherapy.

When chemotherapy is given to patients with osteosarcoma, it is frequently started before the main osteosarcoma surgery. This is done to start the treatment against the disease that might have spread as soon as possible. In addition, the known tumor, where the disease started, may get smaller, potentially making surgery easier. Chemotherapy typically continues after surgery. The total length of chemotherapy treatment varies, but may be between four and nine months of total treatment.

Targeted Therapy

Targeted therapies are medications that work on the cellular level to change the way the body’s cells are behaving. Two common targeted therapy classes for osteosarcoma are kinase inhibitors and mammalian target of rapamycin (mTOR) inhibitors. These treatments block certain proteins that cancer cells use to divide and grow.

Who Treats Osteosarcoma?

People receiving treatment for osteosarcoma are usually cared for by a multidisciplinary team of doctors, nurses and clinical specialists with expertise in bone cancers. This team may include:

• Medical oncologists, who specialize in medicines like chemotherapy drugs
• Surgical oncologists trained to perform biopsies and procedures to remove tumors
• Orthopedic surgeons, who specialize in operating on bones, joints and muscles
• Radiation oncologists with expertise in a wide range of radiation therapy techniques
• Radiologists, who are specialists in diagnosing and assessing cancer tumors
• Pathologists, who evaluate tests and biopsies to diagnose cancer and monitor treatment
• Supportive care providers to help patients manage the physical and emotional impact of cancer and its treatments

Children and adolescents who are diagnosed with osteosarcoma work with pediatric cancer experts who specialize in treating those aged 18 and under.

Osteosarcoma Survival Rate

The overall five-year relative survival rate for people with osteosarcoma is between 60% and 70%, meaning that those diagnosed with the condition are 60% to 70% as likely to survive beyond five years after diagnosis as those who do not have this cancer type.

In a given person, the success of treatment may be affected by a number of factors. Perhaps the most important is how widespread the disease is when it is diagnosed.

Localized osteosarcoma: The five-year relative survival rate is 60% to 75% for those whose cancer is contained to the bone where it started.

Metastatic osteosarcoma: The five-year relative survival rate is 5% to 30% for those whose cancer has spread to other parts of the body like the lungs.

It’s important to note that, even when the disease has spread in the body, it may be curable with proper treatment.