Desmoid Tumors

Desmoid tumors – also called aggressive fibromatosis – are noncancerous tumors that develop in connective tissue. These rare tumors may appear anywhere in your body. But they typically form in your belly, arms and legs, or head and neck.

Desmoid tumors don't spread (metastasize). Most grow slowly. But some are locally aggressive or locally infiltrative. This means they can grow fast. And when they do grow, they may become deeply embedded in nearby tissue. This can make them difficult to remove with surgery.

Often, desmoid tumors come back (recur) after treatment. But everyone's prognosis is different.

Types

Types of desmoid tumors include:

• Abdominal wall desmoid tumors: These affect the wall of tissue that surrounds organs in your belly, like your stomach.
• Intra-abdominal desmoid tumors: They grow in mesentery, the tissue that surrounds your intestines.
• Extra-abdominal desmoid tumors: They develop in places other than your belly and abdominal wall. Usually, they start in your shoulders, upper arms, chest wall and upper legs. But they can also affect your head and neck.

Symptoms of desmoid tumors

Desmoid tumors don’t always cause symptoms. But they can if they get big enough to press on nerves or nearby organs. When they do, symptoms may include:

• A lump or swollen area, usually in your arms, legs or belly
• Nausea and vomiting from a tumor in your belly
• Pain or a tingling sensation from a tumor pressing on nearby nerves, organs or blood vessels
• Trouble moving your arm or leg

Not every lump or bump is a desmoid tumor, but you should talk to a healthcare provider if you have a lump or bump that’s larger than 2 inches, keeps getting bigger or hurts.

Desmoid tumor causes

A desmoid tumor develops when connective tissue cells mutate (change) and multiply. Eventually, they form a tumor.

Doctors don't know why the mutations happen in the first place. But they have found several gene mutations that are common in desmoid tumors. This information helps them design treatments that target the mutations and slow tumor growth.

Risk factors

Risk factors for desmoid tumors include:

• Younger age: Most people diagnosed are between ages 30 and 40.
• Being female: Often, females are diagnosed during pregnancy or shortly after. Usually, the tumors are in the abdominal (belly) wall. Since estrogen levels are high during pregnancy, some experts believe there’s a connection between high estrogen and desmoid tumors.
• Having familial adenomatous polyposis (FAP). About 5% to 10% of people with FAP develop desmoid tumors. The tumors usually arise where you had previous surgery to remove a colon polyp.
• Trauma. Research shows having a serious injury or being repeatedly injured in the same place on your body increases your risk of developing a desmoid tumor.

How doctors diagnose this condition

Your healthcare provider will do a physical exam and ask you about your symptoms. They may recommend:

• Imaging tests: The most common ones are a CT scan and an MRI. They allow providers to see the tumor inside your body.
• A biopsy: They'll remove tissue from the tumor and view the cells beneath a microscope. This is the only way to confirm the type of tumor.

You may need more tests if your provider thinks you may have FAP. Most people with desmoid tumors don’t have this condition. But if you do, it’s important to know since people with FAP are at increased risk of colon cancer.

How are desmoid tumors treated?

Healthcare providers often treat desmoid tumors the same way they treat cancerous tumors. This means you’ll likely work with many healthcare providers, including an oncologist. In the past, surgery was the most common treatment. Since these tumors commonly recur after surgery, current treatments rely mostly on medications. Other treatments include:

• Active surveillance (watchful waiting): If you have a slow-growing tumor that isn’t causing symptoms, your provider may monitor you. You’ll get regular imaging so that if the situation changes, you’ll get treatment as soon as possible.
• Surgery: You may need surgery if a tumor is growing fast and causing severe symptoms. Or, you may get surgery if the tumor puts you at risk of serious complications, like a bowel obstruction.
• Targeted therapy: These medications work by targeting genes or proteins that help desmoid tumors grow. Your provider may recommend treatment using a tyrosine kinase inhibitor (TKI).
• Cryoablation: This procedure is also an alternative to surgery. You may get it if you have a small desmoid tumor in places other than your belly (like your arms and legs).
• Chemotherapy: Drugs may be used to shrink or get rid of desmoid tumors. Results are mixed when it comes to how effective this treatment is.
• Hormone therapy: Tamoxifen may keep desmoid tumors from growing.
• Radiation therapy: Radiation can be used to shrink or eliminate a tumor, alone or along with other treatments.

When should I see my healthcare provider?

You’ll see your healthcare provider regularly after treatment. This is because desmoid tumors often come back. It’s common to get follow-up exams and imaging every six months for the first three years. If you’re not having issues, the check-ups may lessen to every year or every other year.

Your provider will monitor your progress to decide how often you’ll need checks.

What can I expect if I have this condition?

Every desmoid tumor diagnosis is different. For some people, tumors don’t cause symptoms. In 2 out of 10 people, they disappear without treatment. But for other people, they grow so big that they can put your health at risk.

The type of mutation helps healthcare providers predict how aggressive a desmoid tumor will be. It provides information about how likely it is to come back after treatment. But nothing is certain.

This is why it’s important not to assume that things will get better on their own. A desmoid tumor isn’t cancer. But it’s serious enough that your healthcare provider needs to monitor it.

What are the survival rates of desmoid tumors?

Desmoid tumors aren’t typically life-threatening. But they can be an ongoing issue you have to manage.

The more important number is the recurrence-free survival rate. This is how many people don’t have tumors grow back after treatment. The five-year recurrence-free survival rate ranges from as low as 23% to as high as 65%. Much depends on the type of mutation.

Your healthcare provider can explain what you should expect based on your diagnosis.