What Is Sarcoma?

A rare form of cancer affecting bones and connective tissues

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Sarcoma is a rare form of cancer that specifically affects connective (mesenchymal) tissues, including:

  • Bone
  • Cartilage
  • Fat
  • Muscle
  • Tendons
  • Nerve fibers
  • Blood and lymph vessels

There are more than 70 types of sarcoma, and symptoms vary by the location and size of the tumor. Sarcomas are diagnosed in the same way as other solid tumor cancers (with imaging and biopsy) and are treated with surgery, chemotherapy, radiation therapy, and newer targeted and immunotherapeutic drugs.

Sarcomas are primary tumors, meaning that they start in bone and connective tissues. Those that start in another part of the body and spread (metastasize) to bone and connective tissues are considered secondary tumors and can be of any cancer type. 

woman with cancer

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Types

Sarcomas are broadly classified as either bone sarcomas or soft-tissue sarcomas, each of which has multiple subtypes.

Bone Sarcomas

Bone sarcomas are primary bone tumors. The most common types include:

Bone Cancer Prevalence

Around 3,600 people are affected by bone sarcoma in the United States every year. Primary bone sarcomas account for less than 0.2% of all cancers, but bones can be the site of spread for cancers that started elsewhere.

Soft Tissue Sarcoma

Soft-tissue sarcomas are also primary tumors affecting tendons, muscles, vessels, fat, nerve fibers, and other soft connective tissues. Some of the most common types include:

  • Alveolar sarcoma: Affects soft tissues such as muscle, fat, or nerves
  • Angiosarcoma: Forms in the lining of the blood and lymph vessels
  • Clear cell sarcoma: Found in the feet, hands, and limbs
  • Epithelioid sarcoma: Begins in the soft tissue of the skin, usually on a finger, foot, hand, or limb
  • Fibrosarcoma: Starts in the fibrous connective tissues around the tendons
  • Gastrointestinal stromal tumor (GIST): Occurs anywhere in the digestive tract
  • Kaposi sarcoma: Forms under the skin, in lymph nodes, in the lining of the throat, mouth, nose, and other organs
  • Leiomyosarcoma: Typically develops in the smooth muscles such as abdominal organs
  • Liposarcoma: Begins in the fat cells, most commonly in the limbs, muscles, or abdomen
  • Malignant fibrous histiocytoma (MFH): Typically found in the muscles and tendons, rarely in bones
  • Malignant mesenchymoma: Soft tissue tumors that contain two or more subtypes of sarcoma and typically begin on the neck, head, or limbs
  • Malignant schwannomas: Form in the tissues around the nerves
  • Neurogenic sarcoma: Develops on the nerve sheath
  • Rhabdomyosarcoma: Forms in skeletal muscle
  • Synovial sarcoma: Found in the limbs, near joints and affects muscles or ligaments
  • Uterine sarcoma: Starts in the muscular layer of the uterus

Soft Tissue Sarcomas

Soft-tissue sarcomas only account for 0.7% of all cancers in the United States (or just over 13,000 diagnoses).

Symptoms

The symptoms of sarcoma vary by the type, location, and extent of the malignancy. Some, like Kaposi sarcoma, may only cause skin lesions but no other overt symptoms. Others, like rhabdomyosarcoma of the kidneys, can be extremely aggressive and rapidly spread to the liver, lungs, and other sites.

Bone Sarcoma

The most common first sign of bone sarcoma is pain in the affected bone. The pain may come and go or be worse during certain times, such as at night or during activity. As the disease progresses, the pain will become constant and be more intense when active.

There may also be swelling or a lump under the skin at the pain site. Often, this symptom does not become noticeable until a while after the pain begins. If the cancer is in the bones of the neck, it may cause difficulty with swallowing. If the bones of the spine are affected, pressure on the nerves can lead to back pain, limb or abdomen numbness and weakness, and trouble urinating or passing stool. If the nerve cells become damaged from pressure, paralysis may occur.

The most common site for osteosarcoma to spread, or metastasize, is the lungs. More rarely, it can also spread to the bones.

Rarely, sarcomas may be associated with increased calcium levels (hypercalcemia), and they might cause kidney stones, constipation, confusion, or heart problems.

Soft Tissue Sarcoma

One of the most notable signs of soft-tissue sarcoma is the development of a lump or nodule. The lump tends to be painless, firm, and fixed in place, and can occur on the arms and legs two-thirds of the time. The other third occurs on the head, neck, trunk, abdomen, and retroperitoneum—the space behind the abdominal wall that contains part of the aorta, inferior vena cava, the pancreas, and kidneys. 

Often, there are no other symptoms apart from a lump. If the lump grows large enough while going unnoticed, it can cause symptoms such as pain, swelling, edema, and interference with the functioning of bones, nerves, and blood vessels.

If the lump is located in certain areas, it can cause gastrointestinal tract obstruction, leading to symptoms such as loss of appetite, constipation, and cramping. Large sarcomas that press on nerves can lead to neurological issues, and those in the limbs can cause deep vein thrombosis.

Causes

Scientists don’t fully understand what causes sarcoma, although certain risk factors are strongly associated with the disease.

Bone Sarcoma

Bone sarcomas are linked to environmental factors and inherited genetic mutations. Exposure to radiation and specific agents found in chemotherapy drugs (alkylating agents) increases the risk of osteosarcoma and other bone cancers. Inherited genetic syndromes, including Paget’s disease and Li-Fraumeni syndrome, are also strongly linked to the disease.

Soft Tissue Sarcoma

Many soft-tissue sarcomas—particularly pediatric cancers like alveolar sarcomas—are linked to sporadic genetic mutations, some of which may develop while an embryo is forming. Others are linked to inherited genetic syndromes like Li-Fraumeni, neurofibromatosis type 1, and familial adenomatous polyposis. Environmental risk factors include prior exposure to radiation, industrial chemical vinyl chloride, and previous lymphedema history.

Age also plays a role. While most people with soft-tissue sarcomas are over 50, some subtypes are often seen in children.

Diagnosis

Both bone sarcoma and soft-tissue sarcoma are diagnosed with a combination of a physical examination, imaging studies, and a biopsy. Lab tests are less useful for diagnosing sarcoma and, in many people with soft-tissue sarcoma, general blood tests will show normal results. There are some small differences in the tests and procedures used.

Bone Sarcoma

The primary diagnostic imaging tool for bone sarcomas is X-rays. Other imaging tools that may be used include computerized tomography (CT), bone scintigraphy, or magnetic resonance imaging (MRI). 

Biopsies can be done with a needle or an incision. Methods include:

  • Fine-needle aspiration (FNA)
  • Core needle biopsy
  • Surgical bone biopsy

The type of biopsy performed depends on the location of the tumor. A biopsy removes a small sample of tissue that is then examined with a microscope to make a definite diagnosis. When needle biopsies are performed, a tissue sample is removed through a small hole created in the bone. If a biopsy requires an incision, a small cut is made in the tumor.

Lab tests such as a blood test might be done. Alkaline phosphatase and lactate dehydrogenase levels tend to be elevated with osteosarcoma and Ewing sarcoma. However, high levels of these do not mean cancer is present. During high cell activity, such as when children are growing or a bone is healing from a break, alkaline phosphatase levels are also high. More tests will need to be done to determine if bone sarcoma is present.

Soft Tissue Sarcoma

Imaging techniques used to diagnose soft tissue sarcoma include:

  • MRIs
  • Positron emission tomography (PET) scans
  • CT scans
  • Combination PET-CT scans

These tools can point to a possible sarcoma diagnosis, but a biopsy will be required to confirm the diagnosis and determine the type of sarcoma present. MRIs are well suited for imaging soft tissues, but CT may be more useful for diagnosing sarcoma in the chest or abdomen.

Either a needle or incision biopsy can be used, depending on the location of the tumor. A pathologist specializing in soft tissue sarcomas may examine the tissue extracted during a biopsy. Imaging tools such as an ultrasound or MRI may help maneuver the needle into the tumor. Since further surgery is often needed to remove soft tissue sarcomas, incision biopsies are not usually performed. Most doctors prefer to use FNA or core needle biopsy and will only consider surgery if lab evaluations are inconclusive or a tumor is hard to reach.

Staging and Grading

Diagnosis of where the cancer is in the body, where it may have spread, and if other parts of the body are affected is called staging. Testing is performed to discover the staging of cancer, and this information guides the course of treatment and helps determine the patient’s chances of recovery (prognosis). Different types of cancer have unique staging criteria, but the TNM (tumor, node, metastasis) staging guide is used for all.

TNM staging uses information on:

  • The tumor’s size and location
  • Whether or not it has spread to the lymph nodes and how
  • Whether and how extensively cancer has spread to other parts of the body

These results are taken into account to determine the stage of cancer, from 1 to 4, which then determines treatment. Stages 1 to 3 indicates the tumor's size and its spread to surrounding tissues, whereas stage 4 indicates that cancer has spread to farther reaching areas of the body.

Doctors also use a grading system to tell how similar the cancer cells are to healthy cells under a microscope. Cancer cells that resemble healthy cells are called “well-differentiated” or “low-grade tumor,” intermediate grade tumors are “moderately-differentiated,” and cancer cells that are unlike healthy cells are called “poorly-differentiated” or “high-grade tumor.”

Lower-grade tumors typically indicate less chance of spreading quickly, and therefore, a more favorable prognosis. The higher the grade, the more aggressive treatment may need to be. In the case of soft tissue sarcoma, grading is of vital importance for determining prognosis.

The staging and grading, along with the patient’s performance status—how well they can perform daily tasks and tolerate treatments—and other factors help inform treatment decisions and the overall prognosis.

Treatment

Although sarcoma treatment can vary by the type of cancer involved, surgery remains the most common treatment in the early stages. Chemotherapy or radiation may be used before surgery to shrink the tumor (neoadjuvant therapy) or after surgery to clear any remaining cancer cells (adjuvant therapy).

Medication use, also called systemic therapy, includes:

  • Immunotherapy
  • Chemotherapy
  • Targeted therapy

These can be used simultaneously, individually, or in combination with surgery for bone and soft tissue sarcoma.

Bone Sarcoma

The course and type of treatment will vary depending on the stage and grade of cancer. For low-grade sarcomas that start in the bone, surgical removal of the tumor and surrounding area is typical. For a high-grade primary bone sarcoma, surgery can also be combined with other treatments such as medications and radiation.

Where amputation was once a common facet of bone sarcoma treatment, limb-sparing surgery can now be used in 90% of cases combined with chemotherapy. When the tumor is extracted, surrounding bone tissue is also removed in case cancerous cells have spread. Most of these surgeries can spare the limb, although amputations can still be necessary, depending on the tumor’s size and location. 

Advanced malignancies may still require amputation or a type of surgery called a rotationplasty in which a section of bone is removed with the uninvolved ends rotated and reattached. Surgery is also used to treat bone sarcoma that has spread (metastasized) to other areas of the body.

Soft Tissue Sarcoma

The treatment of soft-tissue sarcoma varies by type, location, and stage. In most cases, stage 1 and stage 2 tumors are surgically removed and treated with adjuvant radiation. For stage 3 and some stage 2 malignancies, chemotherapy would also be used.

For stage 4 soft-tissue sarcomas, surgery is typically avoided as it rarely improves outcomes. In such cases, radiation or chemotherapy may be used alone or in combination to shrink the tumor and slow disease progression. 

On rare occasions, surgery may be used to remove the primary tumor and metastases, usually when a small number of metastases have spread to the chest cavity. Even so, the risk of recurrence is high.

Prognosis

In general, the survival rate for soft-tissue sarcoma is better than that of the main type of bone cancer, osteosarcoma. Overall, sarcoma has a 5-year survival rate of 65%. The actual survival rate for each patient depends on factors such as:

  • Where the tumor is located
  • If, where, and how much it has spread
  • How quickly the cancer cells are spreading
  • When the cancer is found

Osteosarcoma has one of the poorest prognoses in children and teens, even with aggressive treatment. According to the American Cancer Society, the overall 5-year survival rate for children and teens with osteosarcoma is 69%. Even so, there are some bone sarcomas, like chondrosarcoma and chordomas, that have far more optimistic outlooks.

Generally speaking, sarcoma tends to have poorer outcomes than other more common types of cancer (such as carcinoma) in the same organ. For example, uterine sarcoma has an overall 5-year survival rate of 42% compared to endometrial carcinoma which has an overall survival rate of 81%.

Survival rates are based on epidemiologic data collected by the National Cancer Institute, called the SEER database. For this classification system, the stages are defined by whether the cancer is localized (limited to the primary tumor), regional (affecting nearby tissues), or distant (metastatic).

Survival rates are estimates only and any individual patient will have a unique prognosis. Since these statistics are taken every 5 years, they may not always account for newer forms of treatment that have been in use within the current 5 years.

The 5-year survival rates apply to when the cancer is first diagnosed and do not apply to when cancer may have spread or has been treated.

5-Year Survival Rates by Sarcoma Type
Osteosarcoma 60%
Chondrosarcoma 78%
Chordoma 82%
Soft-tissue sarcoma 65%
Gastrointestinal stromal tumors (GIST) 83%
Uterine sarcoma 42%
All SEER stages combined (American Cancer Society)

A Word From Verywell

Bone and soft tissue sarcoma are rare, and if you are experiencing lumps or other symptoms, chances are that it is not cancer. Make an appointment with your doctor to rule out any suspicions.

If you or a loved one has been diagnosed with sarcoma, follow your doctor's advice and treatment plan. Know that there are options available for treatment.

As distressing as a sarcoma diagnosis may be, new treatments are being developed every year that increase both survival times and disease-free survival, even in those with stage 4 disease. Drugs targeting uncommon forms of sarcoma are increasingly available. Talk to your doctor about what treatment options are available for you.

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