When you picture a tumor, you might think of a fast-growing, aggressive cancer that spreads throughout the body. But desmoid tumors are different — they don’t have malignant potential, meaning they don’t spread to other parts of the body. However, they do share some characteristics of cancer, which can lead to confusion.

In this article, we’ll explain how desmoid tumors differ from cancer. We’ll also explore how their treatments overlap with those for cancer. To learn more about desmoid tumors, talk to your desmoid tumor specialist.

What Are Benign and Malignant Tumors?

According to JAMA Oncology, a tumor is an “abnormal mass in the body that grows due to cells reproducing too much or not dying when they’re supposed to.” Doctors classify tumors as benign or malignant based on their characteristics.

Benign tumors are noncancerous. They usually grow slowly over time and stay in a general area without spreading. When you take a close look at a benign tumor, it often has distinct borders. Benign tumors don’t invade or grow into other nearby tissues or organs.

In most cases, benign tumors don’t cause any major issues. They can press on nearby structures and cause pain or discomfort if they grow too large. If a benign tumor causes symptoms, it’s usually removed with surgery. Some benign tumors can turn cancerous if they’re left untreated. For example, colon polyps are often removed from your colon because some can cause colon cancer.

Malignant tumors are cancerous growths that spread into nearby areas of tissue. They can infiltrate or grow deep within organs and tissues. If cancer reaches nearby blood vessels or the lymphatic system, it can spread to other parts of the body. This is known as metastasis.

Desmoid Tumors Have Benign and Malignant Characteristics

Desmoid tumors have characteristics of both benign and malignant growths. For example, desmoid tumors grow slowly and only spread to nearby tissues. But they’re not completely harmless abnormal growths.

There’s a reason why desmoid tumors are also known as aggressive fibromatosis or deep fibromatosis. If these tumors become large enough, they can grow into other structures close by. Desmoid tumors can also press on organs, nerves, or bones, causing pain and discomfort.

It’s also important to note that desmoid tumors don’t metastasize like cancers do. Even though they don’t spread to distant parts of the body, these growths can significantly affect your quality of life.

Some people are more likely to develop multiple desmoid tumors at the same time, but this isn’t due to metastasis. Instead, it’s called multifocal disease. Studies show around 1 percent to 3 percent of people with desmoid tumors have multiple growths.

Cancer Specialists Treat Desmoid Tumors

Although desmoid tumors are noncancerous, they’re treated by cancer specialists. This is because both benign and malignant tumors develop when cells grow uncontrollably. Many treatment options for desmoid tumors and cancer work by blocking cell growth and division.

In most cases, doctors simply monitor desmoid tumors over time — an approach known as active surveillance. This strategy is best for slow-growing tumors that don’t change much or cause many symptoms. For more aggressive, faster-growing tumors, additional treatment may be necessary. Possible treatments for desmoid tumors include targeted therapy, chemotherapy, and, in rarer cases, surgery and radiation therapy. These treatments are also used to treat cancer.

Targeted Therapies

Targeted therapies block proteins that desmoid tumor cells use to grow and divide. In November 2023, the U.S. Food and Drug Administration (FDA) approved the first medication for desmoid tumors — nirogacestat (Ogsiveo). Nirogacestat is a type of targeted therapy called a gamma-secretase inhibitor.

Another type of targeted therapy called tyrosine kinase inhibitors (TKIs) is sometimes used for desmoid tumors. These drugs aren’t FDA-approved for desmoid tumors but are used off-label, meaning they’re prescribed for a purpose different from what they were originally approved for. They include:

• Sorafenib (Nexavar)
• Imatinib (Gleevec)
• Sunitinib (Sutent)
• Pazopanib (Votrient)

Chemotherapy

Chemotherapy uses toxic drugs to kill cancer cells. Chemotherapy may also be used for desmoid tumors. Your doctor may use a combination of drugs to try and shrink your desmoid tumor.

Chemotherapy affects all rapidly dividing cells in the body — including your healthy cells. This means you may experience side effects from the treatment, including hair loss and nausea.

Radiation Therapy

Radiation therapy, also known as radiotherapy, is another cancer treatment that is sometimes used for desmoid tumors. This approach uses high-powered X-rays to target and damage DNA in tumor cells. In most cases, radiation therapy isn’t recommended for desmoid tumors. This treatment raises the risk of secondary sarcomas in the body’s soft tissues. Radiation therapy can be used for desmoid tumors in challenging locations where surgery isn’t an option, especially if the tumors cause significant symptoms.

Hormone Therapy

Some older research suggests that desmoid tumor cells use hormones to grow and spread. Hormone therapies like tamoxifen, a drug used to treat breast cancer, were once used for desmoid tumors. This approach isn’t generally recommended anymore.

Does Taking Cancer Treatment Mean You Have Cancer?

It can be scary to meet with a cancer specialist (oncologist) and start treatment. But it’s important to remember that desmoid tumors are not cancers. Just because you’re taking these treatments, it doesn’t mean you have cancer.

The Desmoid Tumor Research Foundation notes that a soft tissue cancer (sarcoma) specialist is best for managing desmoid tumors. They’re highly knowledgeable in diagnosing and managing these rare tumors. You may meet with multiple specialists to make your desmoid tumor treatment plan.

Talk With Others Who Understand

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

Are you living with a desmoid tumor? Do you have questions about whether it’s benign or malignant? Share them in the comments below, or start a conversation by posting on your Activities page.