What is a desmoid tumor?

A desmoid tumor is a rare fibrous growth that can start in the arms, legs, or torso (body). They most commonly grow in the abdomen (belly).

These tumors start in connective tissue, which is found throughout your body. Connective tissue supports and protects other tissues and organs.

Other names for desmoid tumors are aggressive fibromatosis, desmoid-type fibromatosis, and deep fibromatosis.

How do desmoid tumors behave?

Desmoid tumors don’t spread to other parts of the body. But these tumors can grow quite large and lead to disability and severe (very bad) pain. In rare cases, they invade vital organs and lead to severe problems, including death.

Desmoid tumors are related to a group of cancers called soft tissue sarcoma and are treated by cancer doctors.

In some cases, desmoid tumors can be monitored (watched) for a period of time. However, some desmoid tumors may need treatment sooner. They include tumors that cause symptoms, such as pain or loss of function, or that can harm vital organs. Desmoid tumors should be treated by doctors with special training in caring for people with soft tissue sarcoma.

Treatments for desmoid tumors can vary widely. They include active monitoring, chemotherapy, targeted therapies, cryoablation, surgery, or research studies, also known as clinical trials.

What causes a desmoid tumor?

Most desmoid tumors seem to be linked to a genetic change (mutation or variant) in the CTNNB1 gene. Desmoid tumors linked to a CTNNB1 mutation often start during or after pregnancy.

When this genetic change happens in a connective tissue cell, the gene tells the cells to keep growing. The cells grow so much they form a tumor. The tumor can get big enough that it harms nearby healthy tissue.

Some desmoid tumors are caused by an injury. Lesions that start during pregnancy are on the wall of the abdomen (belly). They may go away on their own.

In rare cases, desmoid tumors are linked to a condition that’s inherited (it runs in your family) called familial adenomatous polyposis (FAP). It’s pronounced fuh-MIH-lee-ul A-deh-NOH-muh-tus PAH-lee-POH-sis.

FAP raises your risk for hundreds to thousands of polyps (growths of tissue) in your colon and rectum. But it can also cause desmoid tumors to form if you have a kind of FAP called Gardner’s syndrome.

Out of every 100 people who have FAP, at least 10 will get a desmoid tumor. People with FAP need to be seen in a specialty clinic. They may need a colonoscopy, an endoscopy, or both.

What are the signs and symptoms of a desmoid tumor?

The most common sign of a desmoid tumor is a lump in the arms, legs, or abdomen (belly). Sometimes the lump is painful. There also can be swelling in the area that has the tumor.

If the tumor is in the abdomen, you may have cramps or nausea (feeling like throwing up).

How is a desmoid tumor diagnosed?

Doctors use imaging to find desmoid tumors. A magnetic resonance imaging (MRI) scan or computed tomography (CT) scan can show the tumor’s size and location.

Desmoid tumors rarely spread to other parts of the body, but they can grow in many places. You will need a biopsy (a procedure to get a sample) to be sure of the diagnosis.

Desmoid tumors are rare, and so many doctors lack experience in diagnosing and treating them. It’s important to get a diagnosis from a care team that regularly treats desmoid tumors. They will use special methods to look for the CTNNB1 mutation in the biopsy sample. These include a PCR test (also called a molecular test) or MSK-IMPACT^® (MSK’s tumor genetic test). Information from these tests helps doctors tell desmoid tumors from other types of sarcoma and choose the best treatment.

Why should I come to Memorial Sloan Kettering Cancer Center (MSK) for treatment of my desmoid tumor?

At MSK, we have a team of experts in:

• Quickly diagnosing desmoid tumors with MSK’s Rapid Diagnosis program.
• Treating desmoid tumors.
• Research studies, called clinical trials, that lead to new treatments for these tumors.
• Researching desmoid tumors in our laboratories to learn more about the best way to treat them.

What is the treatment for a desmoid tumor?

Our doctors base their treatment recommendations on the kind of tumor you have. Treatment depends on the desmoid tumor’s size and location.

Surgery to remove the desmoid tumor has been the most common treatment in the past. But we now have a number of other treatment options for people with desmoid tumors. MSK offers the following treatments:

• Active surveillance, also known as watchful waiting. This can be a good option for some people, but not everyone. Your care team closely monitors the tumor with regular scans.
• Chemotherapy.
• Targeted therapy, either as part of standard care or through a research study, also called a clinical trial.
• Interventional procedures:
  • Cryoablation uses CT imaging to guide the placement of a needle into the tumor. Freezing then kills tumor cells. This method does not use surgical incisions (cuts).
  • Injecting the arteries that feed the tumor with beads that carry chemotherapy drugs.
• Surgery. This can be an option for some people, but not everyone.

What is the treatment for a desmoid tumor that has come back?

Desmoid tumors don’t spread to other parts of the body. For that reason, MSK doctors very carefully evaluate the best approach for a desmoid that has come back after treatment.

We look at the genetic information about the tumor. We evaluate the chance it will keeping growing and cause problems. Treatment options are similar to the ones we use when someone is first diagnosed.

What are the chances that a desmoid tumor will come back after treatment?

Everyone has a different risk for recurrence (when the tumor comes back). It depends on many things. MSK has deep experience with desmoid tumors, and developed a prediction tool to better understand that risk. We can evaluate the risk of a tumor coming back 3, 5, and 7 years after surgery. This type of tool is called a nomogram.

MSK strongly recommends people use this nomogram with a doctor very experienced in managing desmoid tumors.

Use our desmoid tumor nomogram.