Soft tissue sarcoma is a rare type of cancer that starts as a growth of cells in the body's soft tissues. Soft tissues include muscle, fat, blood vessels, nerves, tendons and the linings of the joints. Soft tissue sarcoma can happen anywhere in the soft tissues of the body. But it happens most often in the arms, legs and belly.

Soft tissue sarcomas can be serious, but some can have a good outlook, also called prognosis. The outlook is generally better for cancer that is less aggressive and hasn't spread.

When talking about cancers in these tissues, you may hear terms such as soft tissue cancer, malignant soft tissue sarcoma, muscle cancer or connective tissue cancer. These terms do not always mean the same thing. A soft tissue sarcoma starts in the body's soft tissues. But cancer also can spread to soft tissues from other parts of the body. When that happens, it is still called the type of cancer where it first started, not soft tissue sarcoma.

There are more than 50 types of soft tissue sarcoma. Some types are more likely to affect children. Others affect mostly adults. These cancers can be hard to diagnose, partly because they may be mistaken for many other types of growths.

Soft tissue sarcoma treatment usually involves surgery. Other treatments might include radiation therapy and medicines. Treatment depends on the size, type and location of the cancer and how quickly it grows.

Types

There are many types of soft tissue sarcoma. Each type can act differently.

• Angiosarcoma. Angiosarcoma is a type of cancer that forms in the lining of the blood vessels and lymph vessels.
• Desmoplastic small round cell tumor. Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive sarcoma that usually starts in the belly or pelvis. It occurs most often in teenagers and young adults.
• Epithelioid sarcoma. Epithelioid sarcoma often starts in the hands, arms, feet or legs of teenagers and young to middle-aged adults. Epithelioid sarcoma tends to grow slowly at first but can become aggressive.
• Kaposi sarcoma. This cancer forms in the lining of blood vessels and lymph vessels and causes growths of cells called lesions on the skin. Kaposi sarcoma is linked to infection with human herpesvirus 8 (HHV-8). It is more likely to happen in people with weakened immune systems, such as people with HIV.
• Leiomyosarcoma. This smooth muscle sarcoma usually starts in the uterus, belly or legs.
• Liposarcoma. Liposarcoma is a cancer that starts in the fat cells. It can happen anywhere in the body but happens most often in the belly, arms or legs.
• Malignant peripheral nerve sheath tumor. These tumors start in the lining that covers nerves that run from the spinal cord into the body. These nerves are called peripheral nerves.
• Myxofibrosarcoma. This soft tissue sarcoma most often starts in the connective tissue of the arms or legs of older adults.
• Rhabdomyosarcoma. This sarcoma most often starts in muscle tissue or organs such as the bladder and uterus. It usually happens in children.
• Synovial sarcoma. This cancer tends to happen near larger joints such as the hip and knee. It usually affects young adults.
• Undifferentiated pleomorphic sarcoma. This cancer gets its name from the way the cancer cells look under a microscope. Undifferentiated means the cancer cells don't look like the healthy cells around them. Pleomorphic (plee-o-MOR-fik) means the cells grow in many shapes and sizes.
• Dermatofibrosarcoma protuberans. Dermatofibrosarcoma protuberans (DFSP) is a type of skin cancer that starts in the connective tissue cells in the middle layer of the skin. It usually grows slowly.
• Gastrointestinal stromal tumor. Gastrointestinal stromal tumor (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 almost anywhere in the body, including the lining outside of the lungs. They tend to grow slowly.

At first, a soft tissue sarcoma may not cause symptoms. Some possible general signs and symptoms may include:

• A noticeable lump or swelling. The lump may be painless. It may grow over weeks, months or years. It can grow quickly or slowly.
• Pain, tingling or numbness. These symptoms can happen if a sarcoma presses on nearby nerves or muscles.

Some soft tissue sarcomas can cause signs on the skin. For example, dermatofibrosarcoma protuberans (DFSP) can look like a red, purple or brown bump. Kaposi sarcoma may cause spots that look red, purple or brown. Angiosarcoma may look like a bruise.

Symptoms also can be different depending on the body part where a soft tissue sarcoma grows.

Arm or shoulder

Soft tissue sarcomas in the arm or shoulder can look like:

• A noticeable lump or bulge.
• Swelling.
• One arm or shoulder that appears bigger than the other, maybe even causing clothing to feel tighter in that area.

Other possible symptoms include:

• Arm weakness.
• Arm pain.

Belly or back

A soft tissue sarcoma in the belly or back of the belly can cause symptoms including:

• A lump that you may feel.
• Feeling full before you usually would when eating.
• Nausea or vomiting.
• Pain or pressure that gets worse in the belly, back or side.
• Weight loss.

Leg

A soft tissue sarcoma in the calf, the thigh or another part of the leg may look or feel like:

• A noticeable lump or bulge.
• Swelling.
• One calf or thigh that appears bigger than the other, maybe even causing a pant leg to feel tighter in that area.
• Leg weakness.
• Leg pain.

Most lumps are not sarcoma. Sometimes, noncancerous lumps, also 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 under 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.

Do not wait for a lump to become painful before having it checked. A soft tissue sarcoma lump may not hurt.

It's not clear what causes most soft tissue sarcomas.

Soft tissue sarcoma starts when a connective tissue cell gets changes in its DNA. A cell's DNA holds the instructions that tell a cell what to do. The changes turn the connective tissue cells into cancer cells. The changes tell the cancer cells to grow and make more cells. Unlike healthy cells that die as part of their natural cycles, cancer cells keep growing because they do not have instructions to stop.

The cancer cells form a growth, called a tumor. In some types of soft tissue sarcoma, the cancer cells stay in one location. They continue making more cells and cause the tumor to get bigger. In other types of soft tissue sarcoma, the cancer cells might break away and spread to other parts of the body.

The type of cell with DNA changes is what determines the type of soft tissue sarcoma. For example, angiosarcoma begins in cells in the lining of blood vessels, while liposarcoma starts in fat cells.

Factors that may raise the risk of sarcoma include:

• Inherited syndromes. The risk of soft tissue sarcoma can be passed down in families. Genetic syndromes that increase the risk include hereditary retinoblastoma, Li-Fraumeni syndrome, neurofibromatosis type 1, tuberous sclerosis and Werner syndrome.
• Chemical exposure. Exposure to high doses of some herbicides may raise the risk of soft tissue sarcoma, although the evidence is not certain.
• Radiation exposure. Radiation therapy for other cancers can increase the risk of soft tissue sarcomas.
• 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. Human herpes virus 8 (HHV-8) causes Kaposi sarcoma. The risk is higher in people with weakened immune systems, including people with HIV.

Soft tissue sarcoma is diagnosed using imaging tests and procedures called biopsies.

Imaging tests

Imaging tests create pictures of the inside of the body. They can show the size and location of a tumor. They also can show whether a tumor affects nearby tissues and organs and whether cancer may have spread. The tests you have depend on where the tumor is located.

• Computerized tomography (CT) scan. CT may be used to look at tumors in the belly, the organs in the belly and the area behind the organs. CT of the chest may be used to look for cancer that has spread to the lungs.
• Magnetic resonance imaging (MRI). MRI can look at soft tissue tumors in the arms, legs, trunk, head and neck. It can show the tumor and nearby muscles, organs and tissues.
• Positron emission tomography (PET) scan. PET scans usually are not used for the initial diagnosis of soft tissue sarcoma, but they might be used to see whether the cancer has spread or returned. This is called a cancer recurrence.
• X-rays. An X-ray may show whether a tumor starts in bone. A chest X-ray may be done to see whether cancer has spread to the lungs.

Biopsy

A procedure to remove some cells for testing is called a biopsy. A biopsy for soft tissue sarcoma needs to be done in a way that won't cause issues for future surgery. For this reason, it's a good idea to seek care at a medical center that sees many people with this type of cancer. Experienced healthcare teams can select the best type of biopsy.

Types of biopsy procedures for soft tissue sarcoma include:

• Core needle biopsy. This method uses a needle to remove tissue samples from the cancer. Healthcare professionals usually try to take samples from several parts of the cancer.
• Surgical biopsy. Sometimes, your healthcare professional might suggest surgery to get a larger sample of tissue. You may need a surgical biopsy if a tumor is located in an area in which it's hard to safely do a needle biopsy. You also may have a surgical biopsy if core needle biopsy results are not clear.

The biopsy should be looked at in a lab by a type of doctor called a pathologist who has experience diagnosing sarcomas. The pathologist looks at the tissue under a microscope to see whether the cells are cancerous. Other tests in the lab show more details about the cancer cells, such as what type of sarcoma cells they are. Understanding the type of sarcoma is important because it can affect treatment decisions.

Grades

Grade describes what the cancer cells of a soft tissue sarcoma look like under a microscope and how likely the cancer is to grow and spread. This shows how aggressive a tumor is and is part of deciding the stage of the cancer. A pathologist decides the grade by looking at:

• How different the cancer cells look from healthy cells.
• How quickly cancer cells are dividing.
• How much dead tissue called necrosis is in the tumor.

Soft tissue sarcoma grades include the following.

• Grade 1. Low grade. The cancer tends to grow and spread more slowly.
• Grade 2. Intermediate grade.
• Grade 3. High grade. The cancer is more likely to grow and spread.

Not every type of soft tissue sarcoma is graded. This is because a grade does not help predict how aggressive some types of soft tissue sarcoma may be. Examples include angiosarcoma, epithelioid sarcoma and clear cell sarcoma.

Soft tissue sarcoma treatment depends on the type of sarcoma, where it started, its grade and stage, and whether it has spread. The goal of treatment also varies.

For a sarcoma that has not spread, treatment may aim to remove all the cancer with surgery or destroy cancer cells with treatments such as radiation therapy. Sometimes, medicines such as chemotherapy also may be part of treatment.

When a sarcoma cannot be completely removed or has spread to other parts of the body, treatment may focus on using medicines to control the cancer and slow its growth. Treatment also may be used to relieve pain or other symptoms caused by the cancer, which is called palliative care.

Surgery

Surgery is a common treatment for soft tissue sarcoma. The goal is to remove all the cancer. During surgery, the surgeon usually removes the cancer and some healthy tissue around it.

Soft tissue sarcoma often affects the arms and legs. In the past, surgery to remove an arm or a leg was common. Today, other approaches, such as radiation and chemotherapy, usually are used to shrink the cancer. That way the cancer can be taken out without needing to remove the entire limb.

Radiation therapy

Radiation therapy treats cancer with powerful energy beams. The energy can come from X-rays, protons and other sources.

Radiation therapy may be used before, during or after surgery.

• Before surgery. For many soft tissue sarcomas, radiation before surgery may make the cancer easier to remove. Radiation before surgery also can be done on a smaller treatment area and at a lower dose. This may reduce some long-term side effects. However, radiation before surgery can affect the healing process after surgery.
• During surgery. Radiation during surgery allows radiation to be used directly on the area being treated. This limits the effects on some nearby healthy tissues.
• After surgery. Radiation may be used after surgery when there is a higher risk that the surgeon may not have been able to remove all of the cancer cells. This can happen if the cancer is located in an area that makes it difficult to remove much surrounding tissue. Radiation also may be used after surgery when it couldn't be given before surgery, such as when there's a concern about its effects on wound healing.

Chemotherapy

Chemotherapy treats cancer with strong medicines. Healthcare professionals might use chemotherapy before or after surgery. This therapy also can help treat soft tissue sarcoma that's spread to other parts of the body.

Targeted therapy

Targeted therapy uses medicines that attack specific chemicals in cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die.

Your cancer cells might be tested to see whether targeted therapy could be helpful. Targeted therapy can treat certain types of soft tissue sarcoma. It also may treat cancer that comes back or spreads.

Immunotherapy and cell therapy

Immunotherapy uses medicine that helps the body's immune system find and destroy cancer cells. Tumor testing may help show whether immunotherapy could be an option. Immunotherapy may be used for soft tissue sarcoma that's spread to other parts of the body.

Cell therapy also uses the immune system to fight cancer. One type is used to treat advanced synovial sarcoma sometimes. The treatment removes T cells from your blood and changes them in a lab so they can find cancer cells. The T cells are then put back in your body.

Ablation therapy

Ablation is a procedure that applies treatment directly to cancer cells to harm them. Some types of ablation use heat, such as radiofrequency ablation or microwave ablation. Cryoablation uses extreme cold to harm the cancer cells.

Ablation may be an option when surgery isn't possible. It also might be used for some sarcomas that have spread to other parts of the body.

Palliative care

Palliative care focuses on easing symptoms and improving quality of life at any stage of cancer.

For advanced soft tissue sarcoma, you may have surgery, radiation therapy or medicines to ease symptoms even when the cancer can't be fully removed or destroyed. You can receive palliative care along with treatments intended to control the cancer.

Treatment side effects

Cancer treatment can cause side effects and complications. Surgery may affect movement and how the body works. Some people need rehabilitation after treatment. Radiation therapy can make it harder for wounds to heal. Over time, radiation can cause scarring, swelling called lymphedema and joint stiffness.

Chemotherapy and other medicines can cause different side effects depending on the drugs you get. Your healthcare team can explain the short- and long-term effects that are most likely with your treatment plan.

A diagnosis of cancer can feel overwhelming. With time, you'll find ways to cope with the distress and uncertainty of cancer. Until then, you may find it helps to:

• Learn enough about sarcoma to make decisions about your care. Ask your healthcare team about your soft tissue sarcoma. Discuss your treatment options. If you want to, ask about your prognosis. As you learn more, you may become more confident in making treatment decisions.
• Find someone to talk with. Find a good listener who is willing to hear you talk about your hopes and worries. This may be a friend or family member. Meeting with a counselor, medical social worker, clergy member or cancer support group also may be helpful.
• Seek support in others. If you have close friends, family or community members, those relationships may help you deal with soft tissue sarcoma. Trusted others can provide support, including taking care of your home if you're in the hospital. They can give emotional support when you feel overwhelmed by cancer.

Make an appointment with your usual doctor or other healthcare professional if you have any symptoms that worry you. If your care team thinks you might have soft tissue sarcoma, you'll likely be referred to a cancer doctor, called an oncologist. Soft tissue sarcoma is rare and is best treated by someone who has experience with it. Oncologists with this kind of experience are often found within an academic or specialized cancer center.

What you can do

• Write down any symptoms you have. This includes any symptoms that may seem separate from the reason for which you scheduled the appointment.
• Make a list of all medicines, vitamins and supplements that you're taking.
• Ask a family member or friend to come with you. Sometimes it can be hard to remember all the information given to you during an appointment. Someone who comes with you may remember something that you missed or forgot.
• Write down questions to ask your healthcare team.

Preparing a list of questions can help you make the most of your appointment time. List your questions from most important to least important in case time runs out. For soft tissue sarcoma, some basic questions to ask include:

• Do I have cancer?
• Are there other possible causes for my symptoms?
• What kinds of tests do I need?
• What type of sarcoma do I have?
• What stage is it?
• What treatments are available, and which do you recommend?
• What types of side effects can I expect from treatment?
• Are there clinical trials available?
• I have other health conditions. How can I best manage these conditions together?
• What's my prognosis? Ask this only if you want to know. Not everyone does.
• Are there any brochures or other printed material that I can take with me? What websites do you recommend?
• Are there other specialists that I should meet with for my cancer?

What to expect from your doctor

Be prepared to answer some basic questions about your symptoms and your health. Questions might include:

• When did you first notice your symptoms?
• Do you have pain?
• Does anything seem to make your symptoms better?
• What, if anything, appears to worsen your symptoms?
• Do you have any family history of cancer? If so, do you know what type of cancer?

Stage describes how much cancer there is and how far it has spread. For soft tissue sarcoma, stages generally range from 1 to 4. A lower stage generally means the cancer is more limited. A higher stage means it is more advanced.

Both tumor grade and stage help the healthcare team understand the likely outcome of the condition, called the prognosis, and decide the treatment plan.

Healthcare professionals usually summarize the stage as TNM plus grade. TNM stands for:

• T: The size and extent of the primary tumor.
• N: Whether the cancer has spread to nearby lymph nodes.
• M: Whether the cancer has spread to distant parts of the body.
• Grade: The grade of the tumor.

Separate staging criteria are used for sarcomas in different areas of the body. Some soft tissue sarcomas do not have staging.

Your care team can explain how your soft tissue sarcoma's stage is described and what that means for you.

Cancer survival rates tell you the percentage of people who survive a certain type of cancer for a specific amount of time. Cancer statistics often use a five-year relative survival rate. This rate compares survival among people with the cancer and survival among people in the general population.

Survival rates can give you a general idea of how people with soft tissue sarcoma have done over time. But they cannot show exactly what will happen for one person. Outlook can be different depending on many factors. For example, the survival rate for soft tissue sarcoma can vary a lot among the many different types.

But for soft tissue sarcomas in general, the five-year relative survival rate is about:

• 83% for cancer that hasn't spread. The cancer has not spread beyond the place it started. This also is called localized cancer.
• 60% for regional cancer. The cancer has spread nearby to structures or lymph nodes.
• 17% for distant cancer. The cancer has spread to parts of the body distant from where the cancer started. A common site of distant spread for soft tissue sarcoma is the lungs.

Survival rates are based on large groups of people. Your outlook may be different depending on factors such as:

• Type of soft tissue sarcoma.
• Tumor size and grade.
• Whether the cancer has spread.
• Your age.
• Your treatment and how well the treatment works.

Some soft tissue sarcomas can be cured, especially when the cancer has not spread. Tumors that are smaller and have not spread to other parts of the body often have a better prognosis. Your healthcare team can explain what the survival statistics may mean for your specific situation. Talk with your care team if you want to know more about your prognosis.