Sarcoma

Overview

Sarcoma is a rare type of cancer that starts in the bones or the soft tissues. Sarcomas are generally grouped into two broad categories: bone cancer sarcomas and soft tissue sarcoma. Soft tissues connect, support and surround other structures in the body and include muscle, fat, blood vessels, nerves, tendons and other connective tissues.

Sarcomas are different from carcinomas, which make up most cancers in adults. Carcinomas usually start in the cells that make up or line the organs. Sarcomas start in the soft tissues or the bones. This difference is important because sarcomas and carcinomas can behave differently and may need different approaches to diagnosis and treatment.

Sarcomas are not common. They account for less than 1% of cancers diagnosed in adults. There are many different types of sarcomas, and treatment depends on the specific type, where the cancer started, its stage and other factors.

Types

There are many types of sarcomas. Each type can behave differently and may require a different approach to diagnosis and treatment.

Some types of sarcomas don't fit neatly into one category. For example, Ewing sarcoma most often starts in bone but also can develop in soft tissue.

Some tumors start in soft tissues that connect and support, but they are not true sarcomas. Sarcoma specialists may treat these tumors, but they aren't always classified or treated in the same way as soft tissue sarcomas.

Bone sarcomas

• Osteosarcoma. Osteosarcoma starts in bone-forming cells. It most often develops in the long bones, particularly around the knee, and is most common in adolescents and young adults.
• Chondrosarcoma. Chondrosarcoma starts in cartilage-producing cells. It most often occurs in the pelvis, upper leg or shoulder and is more common in adults.
• Ewing sarcoma. Ewing sarcoma most often starts in bone but can start in soft tissue. It occurs most often in children, teenagers and young adults.

Soft tissue sarcomas

• Angiosarcoma. Angiosarcoma is a type of cancer that forms in the lining of the blood vessels and lymph vessels.
• Desmoplastic small round cell tumor (DSRCT). DSRCT is an aggressive sarcoma that usually starts in the abdomen or pelvis. It occurs most often in adolescents and young adults.
• Epithelioid sarcoma. Epithelioid sarcoma often starts in the hands, arms, feet or legs of teenagers and young adults. Other forms can start closer to the center of the body. Epithelioid sarcoma tends to grow slowly. It can come back after treatment.
• Kaposi sarcoma.This cancer can be caused by infection with the human herpes virus 8 (HHV-8) and is more likely to occur in people with weakened immune systems, including people with HIV. It also can happen in people who take medicines to prevent organ rejection after an organ transplant.
• Leiomyosarcoma. This cancer starts in smooth muscle tissue. Many areas of the body have smooth muscle tissue. Leiomyosarcoma most often starts in the uterus, belly or leg.
• Liposarcoma. Liposarcoma is a cancer that starts in the fat cells. It can happen anywhere in the body but occurs most often in the belly, arm or leg.
• Malignant peripheral nerve sheath tumor (MPNST). These tumors start in tissue that surrounds peripheral nerves. These nerves run from the spinal cord into the body. MPNST used to be called neurofibrosarcomas.
• Myxofibrosarcoma. This soft tissue sarcoma most often starts in the arms or legs of older adults. It can grow into surrounding tissues and often comes back in the same area after treatment.
• Rhabdomyosarcoma. This sarcoma starts in muscle tissue. It occurs most often in children and adolescents, although adults can develop it.
• Synovial sarcoma. This cancer tends to happen near large joints, mainly the knees. It usually affects young adults.
• Undifferentiated pleomorphic sarcoma (UPS). The name comes from the way the cancer cells appear under the microscope. Undifferentiated means the cells don't look like the body tissues in which they develop. The cancer is called pleomorphic (plee-o-MOR-fik) because the cells grow in multiple shapes and sizes.

Other related tumors

• Dermatofibrosarcoma protuberans (DFSP). DFSP is a type of skin cancer that starts in the connective tissue cells in the middle layer of the skin. It typically grows slowly but can grow into nearby tissues.
• Gastrointestinal stromal tumor (GIST). GIST is a type of cancer that begins in the digestive system. These tumors happen most often in the stomach and small intestine.
• Solitary fibrous tumor. These tumors start in the connective tissue and can develop almost anywhere in the body. They often occur in the lining around the outside of the lungs. They tend to grow slowly.

Symptoms

Symptoms may vary based on the type of sarcoma. Common signs and symptoms of sarcoma include:

• Bone pain.
• A bone that breaks with no clear cause, such as with a minor injury or no injury.
• Belly pain.
• Weight loss.
• A lump that can be felt through the skin that may or may not be painful.

Most lumps that develop are not sarcoma. Sometimes noncancerous lumps, called benign lumps, develop from fat cells. These are called lipomas.

But a lump that is growing, is larger than about 2 inches (5 centimeters) or is located deep beneath the skin should be checked by a healthcare professional. You can't tell whether a lump is a sarcoma simply by how it looks or feels.

When to see a doctor

Make an appointment with a doctor or other healthcare professional for symptoms that worry you.

Have a lump checked if it:

• Continues to grow.
• Is larger than about 2 inches (5 centimeters).
• Feels like it is deep beneath the skin.

A sarcoma lump may not hurt, so don't wait for a lump to become painful before having it checked.

Also make an appointment if you have swelling near a bone, or lasting bone pain or tenderness, especially pain that occurs at rest or at night. A broken bone that happens after little or no injury also should be evaluated.

Causes

It's not clear what causes most sarcomas. Most sarcomas occur sporadically, meaning they develop without a known cause or an inherited condition that explains why they occurred.

Sarcoma starts when cells in bone or soft tissues develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy cells, the DNA gives instructions that help control when cells grow, multiply and die.

In cancer cells, the DNA changes give different instructions. These changes tell the cancer cells to grow and divide when they shouldn't or to keep living when healthy cells would die. This causes too many irregular cells to accumulate.

The cancer cells might form a mass called a tumor. The tumor can grow to invade and destroy healthy tissue. In time, cancer cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer.

Risk factors

Factors that can increase the risk of sarcoma include:

• Inherited syndromes. Some syndromes that raise the risk of cancer can pass from parents to children. For instance, syndromes that increase the risk of sarcoma include Li-Fraumeni syndrome, familial retinoblastoma and neurofibromatosis type 1.
• Radiation therapy for cancer. Radiation treatment for cancer raises the risk of getting a sarcoma later.
• Lymphedema. Lymphedema is swelling that happens when something blocks or damages the lymphatic system. Lymphedema raises the risk of a type of sarcoma called angiosarcoma.
• Exposure to viruses. The virus called human herpes virus 8 can raise the risk of a type of sarcoma called Kaposi sarcoma in people with weakened immune systems.