Chondrosarcoma is a rare type of bone cancer that begins in cartilage, the flexible connective tissue that cushions your joints and bones. While most cases grow slowly and may not cause symptoms for months or even years, understanding this condition can help patients and their families navigate the diagnosis and treatment journey with greater confidence.
How Common Is Chondrosarcoma?
Chondrosarcoma represents a significant portion of bone cancers, yet it remains quite rare overall. This type of cancer accounts for approximately 20 percent of all primary malignant tumors of the bone, making it the third most common primary bone cancer after myeloma (a cancer of plasma cells) and osteosarcoma (a cancer that forms in new bone tissue).[1][2]
In the United States, chondrosarcoma affects roughly 1 in 200,000 people each year. This means that in a city of one million people, only about five individuals would be diagnosed with this condition annually. Despite being classified as rare, chondrosarcoma represents about 30 percent of all bone sarcomas, which are cancers that develop in bones and soft tissues.[3][4]
The disease shows a slight preference for males over females. When it comes to age, chondrosarcoma is primarily a disease of adulthood and older age. The majority of patients are older than 50 years of age at the time of diagnosis, with the average age being around 51 years. Unlike some other bone cancers that predominantly affect children and adolescents, chondrosarcoma can present at any age but becomes increasingly common as people grow older, particularly affecting those between ages 40 and 75.[5][6]
However, certain rare forms of chondrosarcoma have different age patterns. For example, mesenchymal chondrosarcoma, an aggressive variant, often affects younger adults between ages 19 and 30.[7]
Where Does Chondrosarcoma Develop?
Chondrosarcoma can appear anywhere in the body where cartilage exists, but it shows clear preferences for certain locations. The most common sites of involvement include the bones of the axial skeleton, which refers to the central core of the body. This includes the pelvis, scapula (shoulder blade), sternum (breastbone), and ribs. Following these, the disease frequently appears in the proximal femur (upper part of the thigh bone) and proximal humerus (upper part of the arm bone).[8][9]
The pelvis and hip area are particularly common locations for this cancer to develop. The upper arm, legs, and shoulder blades are also frequently affected sites. In rare cases, chondrosarcoma can occur in the bones of the spine, though this is less common. Involvement of the hands and feet is quite rare.[10]
Sometimes chondrosarcoma develops within benign bone tumors that become cancerous. These non-cancerous growths can undergo malignant transformation, meaning they change from harmless to cancerous over time.[11]
What Causes Chondrosarcoma?
The exact cause of chondrosarcoma remains unclear to medical researchers. What is known is that cancer begins when a cell develops changes, called mutations, in its DNA. Your DNA contains the instructions that tell each cell what to do. When these instructions become damaged or altered, the cell may begin to behave abnormally.[1]
In chondrosarcoma, the mutations tell the cell to multiply quickly and to continue living when healthy cells would normally die. As these abnormal cells accumulate, they form a tumor that can grow large enough to invade and destroy normal body tissue. Over time, some cells can break away from the original tumor and spread, or metastasize, to other areas of the body.[12]
The majority of chondrosarcomas are sporadic, meaning they occur randomly without any clear inherited cause. However, in some cases, the disease may develop from the malignant transformation of pre-existing benign conditions. Specifically, chondrosarcoma can arise from osteochondromas (benign bone growths capped with cartilage) and enchondromas (benign cartilage tumors within the bone). Research shows that malignant transformation occurs in approximately 5 percent of osteochondromas, whether they are multiple or solitary forms.[3][13]
Scientists have identified certain chromosomal abnormalities and genetic changes in chondrosarcoma cells. These include anomalies in chromosomes labeled 9p21, 10, 13q14, and 17p13. Additionally, the amplification of certain genes called MYC and AP-1 transcription factors appears to play an important role in how chondrosarcoma develops. Some studies have also linked the disease to faulty isocitrate dehydrogenase 1 and 2 enzymes, which are also associated with certain brain tumors and leukemias.[14][15]
Risk Factors for Developing Chondrosarcoma
Several factors can increase a person’s risk of developing chondrosarcoma, though having these risk factors does not mean someone will definitely get the disease. Age is one of the most significant risk factors. As mentioned earlier, chondrosarcoma occurs most often in middle-aged and older adults, though it can develop at any age.[16]
Certain genetic disorders significantly increase the risk of developing chondrosarcoma. People with Li-Fraumeni syndrome, a rare hereditary condition, have a higher likelihood of developing various cancerous tumors, including chondrosarcomas. This syndrome is caused by mutations in a gene called TP53, which normally helps suppress tumor growth.[17]
Maffucci syndrome and Ollier’s disease are two related disorders that cause benign tumors to form in cartilage, bone, and skin. Individuals with these conditions face an elevated risk of having their benign tumors transform into chondrosarcoma. A small minority of secondary chondrosarcomas occur in people with these syndromes.[6][18]
Hereditary multiple osteochondromas, sometimes called hereditary multiple exostoses, is another genetic condition that increases risk. This disorder causes multiple benign bone tumors that can disrupt normal bone growth, and some of these growths may eventually become cancerous.[19]
Medical experts believe that in some cases, changes in chromosomes or genes that are not related to an inherited disorder may cause cartilage cells to become cancerous. These changes might occur randomly during a person’s lifetime rather than being passed down from parents.[4]
Symptoms and Warning Signs
Most chondrosarcomas grow slowly, which means symptoms often take months to develop and may be subtle at first. Because of this gradual progression, people might not be aware of a growing tumor until it becomes noticeable or causes discomfort. The slow growth pattern can lead to delays in diagnosis, as symptoms may be mistaken for less serious conditions like arthritis or sports injuries.[1][20]
The most common symptom of chondrosarcoma is pain at the tumor site. This pain typically increases over time and may come and go initially. Many patients notice that the pain gets worse at night, which can disrupt sleep and become particularly bothersome. The pain might start as mild discomfort that can be managed with over-the-counter pain relievers, but it gradually becomes more severe and persistent.[11][21]
Another common sign is a growing lump or area of swelling. Patients may notice a swollen spot or bump on a bone, such as on the arm, leg, or ribs. This lump might be visible or felt when touching the affected area. As the tumor grows, the swelling becomes more apparent and may feel firm to the touch.[22]
Fatigue is another symptom that many patients with chondrosarcoma experience. This isn’t just ordinary tiredness that improves with rest; it’s a profound exhaustion that persists even after adequate sleep. Some people also experience unintentional weight loss, meaning they lose weight without trying to diet or increase their physical activity.[4]
When chondrosarcoma develops in certain locations, it can cause specific symptoms related to that area. For instance, if the tumor presses on the spinal cord, it may cause weakness or problems with bowel and bladder control. Tumors in the pelvis might cause urinary obstruction or a noticeable limp. If the tumor affects an arm or leg, patients may experience decreased movement of the affected limb or increased pain with activity or lifting.[7]
In some cases, a person’s first symptom might be a broken bone at the cancerous site. While many conditions can cause bones to become weak and prone to fractures, any bone that breaks from mild trauma should be investigated by a healthcare provider, as this can occasionally be a sign of an underlying bone tumor.[6]
Prevention Strategies
Unfortunately, there are currently no proven strategies to prevent chondrosarcoma, particularly because the exact cause of the disease remains unknown and most cases occur sporadically without identifiable triggers. Unlike some cancers that can be prevented through lifestyle modifications such as avoiding tobacco or maintaining a healthy weight, chondrosarcoma does not have established lifestyle-related risk factors that can be modified for prevention.[1]
For individuals with genetic conditions that increase their risk of developing chondrosarcoma, such as Ollier’s disease, Maffucci syndrome, or hereditary multiple osteochondromas, prevention focuses on careful monitoring rather than stopping the disease from occurring. Regular check-ups and imaging studies can help detect any malignant transformation of benign tumors at an early stage, when treatment is most likely to be successful.[23]
People with pre-existing benign bone conditions like enchondromas or osteochondromas should maintain regular follow-up appointments with their healthcare providers. If these benign tumors show signs of change, such as increasing in size or becoming painful, prompt evaluation is essential. Being aware of any changes in your body, particularly new or growing lumps or persistent bone pain, allows for earlier medical consultation.[24]
Genetic counseling may be beneficial for families with a history of conditions associated with increased chondrosarcoma risk. A genetic counselor can help family members understand their risk, discuss testing options, and develop appropriate monitoring plans. While this doesn’t prevent the disease, it enables earlier detection and intervention.[25]
How Chondrosarcoma Affects the Body
Understanding what happens in the body when chondrosarcoma develops helps explain both the symptoms patients experience and why certain treatments are used. At the cellular level, chondrosarcoma begins with abnormal changes in cartilage-producing cells. These cells, which should normally create healthy cartilage to cushion joints and support bone structure, instead start producing malignant cartilage tissue.[3]
When doctors examine chondrosarcoma tissue under a microscope, they typically see tumors that are usually greater than 4 centimeters in size. The tumor has a distinctive appearance, often showing a translucent, lobular structure with a blue-grey or white color when cut open. These characteristics help pathologists identify the cancer type when examining biopsy samples.[9]
As the tumor grows, it begins to destroy normal bone tissue around it. The cancer produces abnormal cartilage that gradually expands and invades healthy bone structure. This invasion weakens the affected bone, which explains why some patients experience fractures even from mild trauma. The growing tumor also puts pressure on surrounding tissues, including nerves, blood vessels, and muscles, which causes pain and may limit movement in the affected area.[26]
The body’s immune system normally works to identify and destroy abnormal cells, but chondrosarcoma cells can sometimes evade this immune surveillance. For many years, researchers thought that chondrosarcoma existed in what they called an “immune desert,” meaning it had very few immune cells around it. However, recent studies have shown that immune cells are actually present around these tumors, but they function differently than in other cancers. The tumor creates an environment called the tumor microenvironment that recruits normal cells and may help the cancer cells become more aggressive and avoid being destroyed by the immune system.[15]
Different types of chondrosarcoma behave differently in the body. Conventional chondrosarcoma, which accounts for more than 85 percent of cases, typically grows slowly and is less likely to spread to other parts of the body. Dedifferentiated chondrosarcoma is more aggressive; it starts as typical chondrosarcoma but parts of the tumor change into cells that behave like high-grade sarcomas, growing and spreading rapidly. Clear cell chondrosarcoma tends to grow slowly and rarely spreads, while mesenchymal chondrosarcoma often grows quickly and is more likely to spread to distant sites like the lungs.[4][27]
One significant feature of chondrosarcoma is its resistance to chemotherapy and radiation therapy. Unlike many other cancers, the tumor cells in most chondrosarcomas do not respond well to these treatments. This resistance is related to how slowly conventional chondrosarcoma cells divide and grow, as chemotherapy typically works best on rapidly dividing cells. The structure of cartilage tissue also makes it difficult for chemotherapy drugs to penetrate the tumor effectively. This biological behavior is why surgery remains the primary and most effective treatment for this disease.[12][28]
When chondrosarcoma spreads beyond its original location, it most commonly travels to the lungs. This spread, called metastasis, occurs when cancer cells break away from the primary tumor, enter the bloodstream or lymphatic system, and establish new tumors in distant organs. The likelihood of metastasis depends heavily on the tumor grade and type, with high-grade and certain aggressive subtypes being much more likely to spread.[29]
