Understanding Sarcoma

Sarcoma is a rare cancer that starts in the body's connective tissues, often in an arm or leg. It’s the only solid tumor that can occur at any age and in any part of the body. Sarcomas are easier to treat when discovered early, before cancer has spread from its original site.

There are two main types:

  • Soft tissue sarcomas start in fat, muscles, nerves, blood vessels and deep skin.
  • Bone sarcomas (also called bone cancer) start in bone cells.

A diagram illustrating areas of soft tissue.

Kristina Golsan, R.N. (below), is part of our team-based care at OHSU for patients with bone and soft-tissue tumors.

What is sarcoma?

Sarcoma is a cancer that starts in the body's connective tissues, such as fat, muscles, nerves and bone. Because these tissues fill the body, a sarcoma can develop anywhere, including in the breast and abdomen. Because a large portion of these tissues exist in limbs, many sarcomas start in the arms and legs.

Who gets sarcoma?

Sarcomas are rare. About 15,000 cases are diagnosed each year in the U.S. compared with about 250,000 new cases of breast cancer. Risk factors include:

A young doctor speaking to a patient.Youth: Sarcomas make up a much larger percentage of cancers in children than in adults.

  • Sarcomas make up about 20 percent of childhood cancers compared with about 1 percent of adult cancers.
  • About half of all sarcomas occur before age 40. This may be in part because sarcomas often form during growth spurts.
  • Osteosarcoma and Ewing sarcoma occur most often in children and young adults.

Family history: Families that have certain rare cancer syndromes are more likely to get sarcomas. OHSU offers expert genetic counseling and testing to help patients and families assess and manage risk.

Other: People who've had radiation therapy, who have a damaged lymph system or who've been exposed to certain chemicals also have a higher risk.

Survival rates

It’s important to know that survival rates are averages and can’t predict the outcome for any one patient. Rates also vary by sarcoma type. They are higher when sarcoma starts in an arm or leg.

Soft tissue sarcoma: More than 80 percent of patients survive five years or longer after diagnosis if their sarcoma is found before it spreads from its original site, according to the American Cancer Society. Ten-year survival rates are similar. This suggests that those who survive at least five years are likely to be cured. Survival rates are lower if sarcoma is found after it has spread.

Bone sarcoma: About 70 percent of patients — adults and children — survive at least five years after diagnosis. For osteosarcoma, the most common type, the rate ranges from 60 percent to 80 percent if the cancer is caught before it spreads.

Symptoms of sarcoma

Most often, these symptoms are not caused by sarcoma. But if they persist and no other condition explains them, talk with your doctor.

Signs and symptoms of a soft tissue sarcoma:

  • A lump on an arm or leg, often not painful, that grows over weeks or months
  • Pain in the abdomen
  • Blood in your vomit or stool, or stools that are black and tarry

Signs and symptoms of a bone sarcoma:

  • Pain in the affected bone, first only at night or when using that bone, later frequently
  • Lump or mass, depending on the tumor’s location
  • Rarely, fractures caused by a weakened bone 

Sarcoma types

Soft tissue sarcoma

Soft tissue sarcoma makes up about 80 percent of sarcoma cases. It also comes in dozens of types. Some of the most common ones are:

  • Angiosarcoma: This type forms in blood vessels or vessels of the lymph system, sometimes after treatment with radiation therapy.
  • Fibrosarcoma: This type develops in fibrous tissue in the arms, legs or trunk.
  • Leiomyosarcoma: This type develops in smooth muscle cells, such as in the wall of the uterus, stomach or intestine.
  • Liposarcoma: This type forms in fatty tissue and can occur anywhere in the body.
  • Malignant peripheral nerve sheath tumor: This aggressive tumor forms in a nerve’s protective covering. It’s also called an MPNST.
  • Rhabdomyosarcoma: This type is usually found only in children, with about half of cases diagnosed in patients younger than 10. It usually develops in muscles that are attached to bone and that you can control.
  • Undifferentiated pleomorphic sarcoma: This type usually forms in arms or legs and occurs most often in older adults. It’s usually found in soft tissue but can also develop in bone. It can form in body parts previously treated with radiation therapy.

Bone sarcoma

The most common types are:

  • Osteosarcoma: This is the most common bone sarcoma. It starts in bone cells and most often occurs in ages 10 to about 30.
  • Chondrosarcoma: The second most common type starts in cartilage cells and is rare in children.
  • Ewing sarcoma of the bone: The third most common type often starts in the hip bone, the ribs and the legs, and mostly in children and teens. One type of Ewing sarcoma begins in soft tissue.

Sarcoma staging

Staging plays an important role in treatment decisions by determining factors such as:

  • Whether your cancer has spread
  • If so, how much
  • How aggressive it is likely to be

Soft tissue sarcomas

Cancer experts have changed how they stage soft tissue sarcomas because they are so complex. Your cancer will be staged based on factors that include:

  • The type of soft tissue sarcoma
  • The part of the body it started in
  • The size of the tumor
  • Whether cancer has spread to lymph nodes or other parts of the body
  • The cancer’s grade:
    • How normal or abnormal cells look under a microscope
    • How many cells are dividing (mitotic count)
    • How much dead tissue (necrosis) the cancer contains

Bone sarcomas

Generally, cancer in Stages I through III has not spread outside the bone where it started.

Stage I: The tumor is low grade, meaning its cells don't look much different from normal cells; it’s not growing fast; and it doesn’t contain much dead tissue. It is also confined to the area where it started. In the spine, the tumor is confined to nearby vertical segments of the spine. For the pelvis, the tumor is confined to two pelvic segments.

Stage II: The tumor remains where it started but has a higher grade, meaning cells look more abnormal, and the tumor is growing faster and contains more dead tissue.

Stage III: The tumor is larger or has spread to more bone areas near where it started. It’s also higher grade.

Stage IV: The tumor may be of any grade, but cancer has spread outside the bone where it began. In Stage IVA, cancer has spread to a lung. In Stage IVB, cancer has spread to lymph nodes or other parts of the body besides the lung.

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