Rhabdomyosarcoma is a rare type of soft tissue sarcoma that develops in the skeletal muscles. The disease is most common in children and adolescents. But rhabdomyosarcoma can affect adults, too. And adult rhabdomyosarcoma is often more difficult to treat.

We spoke with sarcoma medical oncologist Andy Livingston, M.D., to learn more about adult rhabdomyosarcoma. He shares the different types of adult rhabdomyosarcoma, how the type affects prognosis and treatment, and what MD Anderson is doing to advance adult rhabdomyosarcoma treatment.

Where does rhabdomyosarcoma start?   

Rhabdomyosarcoma can appear almost anywhere in the body, but the most common locations are the:

• head and neck
• genitourinary system (urinary and genital organs)
• extremities (arms and legs)

What causes rhabdomyosarcoma in adults?

More than 90% of rhabdomyosarcoma cases happen suddenly. So, we don’t really know what causes it. We do know certain inherited genetic conditions put you at a higher risk of developing rhabdomyosarcoma. They include:

• Li-Fraumeni Syndrome
• TP53 gene mutation
• Neurofibromatosis type 1 (NF1)
• Hereditary retinoblastoma

What are the symptoms of adult rhabdomyosarcoma?

Rhabdomyosarcoma symptoms depend on the cancer’s location. Like most soft tissue sarcomas, the most common symptom is a growing, painless lump in the arms or legs.

This is a vague symptom, so it is often overlooked or mistaken for a benign condition.

Other symptoms may include:

• Head and neck: nasal congestion or vision changes
• Genitourinary system: blood in the urine or difficulty urinating
• Enlarged lymph nodes near the affected part of your body

Since it’s so rare, many doctors do not have much experience with adult rhabdomyosarcoma. This is part of the reason many people are diagnosed when the cancer is at an advanced stage.  

If your doctor suspects you have rhabdomyosarcoma, they will usually order an imaging test like a CT scan or MRI. Then you may need a needle biopsy or an excisional biopsy to test the tissue. The biopsy will determine whether it’s cancerous.

How does adult rhabdomyosarcoma differ from childhood rhabdomyosarcoma?

A lot of people think of rhabdomyosarcoma as one disease. But there are different subtypes of rhabdomyosarcoma. They behave differently, and sometimes we treat them differently.

Pleomorphic rhabdomyosarcoma

Pleomorphic rhabdomyosarcoma mainly occurs in adults in their 50s and 60s. It very rarely affects children. It usually shows up in the arm or leg and can grow quickly. We usually treat pleomorphic rhabdomyosarcoma the same way we treat other high-grade soft tissue sarcomas.

Alveolar rhabdomyosarcoma

Alveolar rhabdomyosarcoma usually affects older children, teens and young adults in their 20s, 30s or 40s. It is characterized by the FOX01 gene fusion.

Embryonal rhabdomyosarcoma

Embryonal rhabdomyosarcoma is most common in very young children. It rarely affects adults.  

Typically, we treat alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma similarly to how we treat pediatric cancers. But we may modify the treatment when they’re diagnosed in adults. This could mean changing the medicine or adjusting the dosage. It’s important to know the disease’s subtype because that can inform our treatment: should we treat it similarly to a pediatric rhabdomyosarcoma, or treat it in a different way?

How is adult rhabdomyosarcoma treated?

Treatment for almost all patients with rhabdomyosarcoma – child or adult, regardless of subtype – typically involves:

• chemotherapy,
• surgery and/or
• radiation therapy.

Rhabdomyosarcoma often spreads to other parts of the body. It can spread to nearby lymph nodes, the lungs or sometimes the bone or bone marrow. Sometimes we will see these metastases at the time of diagnosis. Even if a patient only has one tumor, we know that based on the way these tumors behave, it’s likely to spread.

So, we usually do chemotherapy first to shrink the main tumor that we can see. Surgery and/or radiation may follow, depending on the cancer’s stage and grade. After that, we’ll give the patient more chemotherapy to eliminate metastasis and help prevent recurrence.

We can also do fusion testing to help guide treatment. A gene fusion is when two genes are connected in a way that they’re not supposed to be. There is a specific gene fusion called FOX01 that is commonly found in alveolar rhabdomyosarcoma. We know that having that fusion leads to a worse prognosis, so we will often use different treatments on those patients.

What’s the prognosis for adult rhabdomyosarcoma?

Adult rhabdomyosarcoma tends to have a poorer prognosis than childhood rhabdomyosarcoma. We’re not entirely sure why that is, but we think it may be because:

• Pleomorphic rhabdomyosarcoma is a unique subtype.
• Patients are often diagnosed with later-stage or advanced disease.
• There is less unification around treatment. We don’t know if adults can tolerate the treatment as well as children.

There’s a staging system that is often used for rhabdomyosarcoma. Although we can use the TNM system, as we do for many cancers, the staging system that is often applied to rhabdomyosarcoma is a bit more complicated. We know some patients with rhabdomyosarcoma that has spread to other areas can still be cured. This unique staging system helps us better understand the prognosis.

Adult rhabdomyosarcoma is curable. At MD Anderson, we use a multi-modality treatment approach with the intent to cure the disease. Every patient is different. I encourage you to speak with your care team to discuss treatment and prognosis.

What is MD Anderson doing to advance adult rhabdomyosarcoma treatment?

We are trying to determine the best standard treatment for older adults with rhabdomyosarcoma.

Genomic medicine researcher Andy Futreal, Ph.D., and sarcoma medical oncologist and researcher Michael Nakazawa, M.D., Ph.D., contributed to clinical research that studied the molecular drivers of pleomorphic rhabdomyosarcoma. Based on the findings, we’re looking at possibly using immunotherapy to treat the disease.

I’m also leading a clinical trial to see if T-cell therapy can be used to treat patients with advanced or metastatic rhabdomyosarcoma. We’re really trying to look outside the box of standard chemotherapy for patients with rhabdomyosarcoma.

What else should patients and caregivers know about adult rhabdomyosarcoma?

Sarcomas make up about 1% of cancer diagnoses in the U.S. each year. Adult rhabdomyosarcoma cases account for just 3% of those diagnoses.

I see adults with rhabdomyosarcoma almost every day in the clinic. I always tell patients adult rhabdomyosarcoma is extremely rare, but it’s not rare to us. That’s why people come to MD Anderson. 

Any patient diagnosed with adult rhabdomyosarcoma or suspected of having this diagnosis should seek care at a sarcoma center that specializes in seeing and treating this disease.

Request an appointment at MD Anderson online or call 1-877-632-6789.