Desmoid tumors are often treated by sarcoma specialists, so you may wonder, are desmoid tumors sarcomas? In this article, we’ll discuss what desmoid tumors and sarcomas have in common and what makes them different.

What Are Desmoid Tumors and Sarcomas?

Desmoid tumors grow from connective tissue. Connective tissue, or soft tissue, keeps your organs in place and connects your ligaments, muscles, and bones. A sarcoma is a type of cancer in the connective tissue or bone. Sarcomas can spread to healthy tissue, which is what makes it a type of cancer.

Desmoid tumors and sarcomas grow in similar locations and are treated by the same specialists. The main difference is that desmoid tumors do not spread to surrounding tissues and are not considered to be sarcoma. The World Health Organization (WHO) classifies desmoid tumors as “locally aggressive,” meaning they can grow and invade nearby tissues but don’t spread to other parts of the body. They are considered “intermediate,” falling between benign (noncancerous) and malignant (cancerous) tumors. This means that although they aren’t cancerous, they can still cause significant problems where they grow.

How Are Desmoid Tumors and Sarcomas Similar?

Here, we’ll describe the similarities between desmoid tumors and sarcomas and why desmoid tumors may be treated by sarcoma specialists.

1. Desmoid Tumors and Sarcomas Can Begin in Soft Tissue

Desmoid tumors only develop in soft tissue and usually affect your arms, legs, or stomach, but they can grow anywhere in the body. Soft tissue sarcomas are usually found in the arms, legs, or stomach as well.

2. Desmoid Tumors and Sarcomas Are Rare

Both desmoid tumors and sarcomas are rare tumors. Desmoid tumors are a rare soft tissue tumor that affects two to four people per million annually. Sarcomas are also a rare form of cancer. In the United States, there are approximately 18,000 cases of sarcomas diagnosed a year.

3. Desmoid Tumors Share Some Sarcoma Symptoms

Desmoid tumors and sarcomas can both involve the following symptoms:

• Pain
• Swelling, or a lump
• Trouble moving the affected limb
• Nausea/weight loss (for an intra-abdominal desmoid tumor)

4. Desmoid Tumors and Sarcomas Share a Risk Factor

Desmoid tumors are linked to a genetic disorder called familial adenomatous polyposis (FAP). This condition causes colon polyps, or precancerous growths in the colon, that can lead to a desmoid tumor.

One type of FAP is Gardner syndrome, which involves colon polyps as well as tumors in other locations of the body. Gardner syndrome is a risk factor for sarcomas.

5. Desmoid Tumors and Sarcomas Have a Similar Path to Diagnosis

Both desmoid tumors and sarcomas are first examined through a physical exam. This will help your health care provider understand your symptoms.

If a desmoid tumor or sarcoma is suspected, your health care provider may order imaging tests. Both sarcomas and desmoid tumors can be diagnosed via CT scans and MRI.

Sarcomas can also be diagnosed by X-rays and bone scans because they can occur in bone. Sometimes, positron emission tomography (PET) scans are used to diagnose sarcomas.

After imaging scans, a biopsy may be ordered to diagnose a sarcoma or desmoid tumor. A biopsy involves taking a small sample of the tumor tissue for further examination and testing in a lab. This can help with diagnosis and provide information for the best course of treatment.

6. Desmoid Tumors and Sarcomas Can Be Treated By Cancer Doctors

Desmoid tumors are treated by sarcoma specialists, a group of oncologists with sarcoma expertise. Sarcomas specialists have extensive knowledge in treating people with sarcomas. They may also be involved in research and clinical trials. Desmoid tumors and sarcomas share some treatment options, including oral targeted therapies and chemotherapy. Oral targeted therapies are medications taken by mouth that specifically target cancer cells without affecting most healthy cells.

Desmoid tumors may not need to be treated if they’re stable and not causing serious symptoms. Your care team may recommend active surveillance, also known as watchful waiting or observation. If your care team recommends this approach, you will have periodic appointments for them to check your tumor.

How Are Desmoid Tumors and Sarcomas Different?

Desmoid tumors are not a type of sarcoma. In this section, we’ll discuss the differences between desmoid tumors and sarcomas.

1. Sarcomas Are Cancerous

Sarcomas are malignant (cancerous) tumors that spread to surrounding tissues. The main reason desmoid tumors are not sarcoma is because desmoid tumors are not cancerous. Desmoid tumors are a type of noncancerous, or benign, soft tissue tumor. They are considered benign because they do not spread to other areas of the body, but they can grow and become aggressive, potentially damaging surrounding organs and tissues.

2. Desmoid Tumors and Sarcomas Have Different Risk Factors

While FAP is a risk factor for both sarcomas and desmoid tumors, they have some different risk factors, listed below.

Desmoid tumors and sarcomas affect people of different ages. Desmoid tumors are more common in young adults, 20 to 30 years old. Soft tissue sarcomas affect children and adults more often. Bone sarcomas are more common in children, teens, and people over 65 years of age.

Risk factors associated with desmoid tumors include:

• Female sex assigned at birth
• Injury, or trauma, such as abdominal surgery
• Pregnancy
• FAP, an inherited syndrome associated with colon cancer

Risk factors associated with sarcomas include:

• Radiation
• Long-term swelling
• Exposure to viruses
• Exposure to chemicals
• Broken bone

3. Sarcomas Can Occur in Other Parts of the Body

Although desmoid tumors are only found in soft tissues like muscles, blood vessels, tendons, and nerves, sarcomas can also be found in bone. Because sarcomas can also start in the bone, a broken bone is a risk factor for sarcomas, not desmoid tumors.

4. Surgery Is a More Common Treatment for Sarcomas Than Desmoid Tumors

Surgery used to be the main treatment for desmoid tumors. However, it is no longer recommended as a first option because of the high chance that the tumors will return. On the other hand, surgery is often a preferred option for sarcomas.

Sometimes, surgery is still used as a treatment option for desmoid tumors, depending on specific circumstances. The tumor’s size, location, and growth rate and the person’s overall health are important in deciding if surgery is the right choice. Although surgery can remove the tumor, it comes with risks, like possible damage to nearby tissues and the chance that the tumor could come back. Doctors carefully consider each case to determine the best treatment plan, which might also include medication or radiation therapy.

Talk With Others Who Understand

MyDesmoidTumorTeam is the social network for people with desmoid tumors and their loved ones. On MyDesmoidTumorTeam, members come together to ask questions, give advice, and share their stories with others who understand life with desmoid tumors.

Do you have questions about the differences between desmoid tumors and sarcomas? Share your experience in the comments below, or start a conversation by posting on your Activities page.