Rhabdomyosarcoma (RMS or "rhabdo") is a cancerous tumor that develops in the body's soft tissues, usually the muscles. It can affect the head, neck, bladder, vagina, arms, legs, trunk, or just about any body part. Cells from these tumors are often fast growing and can spread (metastasize) to other parts of the body.
RMS is the most common type of soft-tissue cancer in children. Kids can develop it at any age, but it's most common in those between 2 and 6 years old and 15 and 19 years old. Boys tend to be affected more often than girls.
Types of Tumors
The two main types of RMS in kids are:
- Embryonal RMS: This tumor usually develops in the head and neck area, genitals, or urinary tract. It usually occurs in kids younger than 6. Although it's considered an aggressive (fast growing) type of tumor, it usually responds well to treatment.
- Alveolar RMS: This type, which is most likely to occur during the teen years, most often affects the arms or legs, chest, or abdomen. It, too, is fast growing but often more difficult to treat. Most kids with this type of tumor need intensive treatment.
The cause of RMS is unclear, but doctors know that certain medical conditions can make some children more likely to develop rhabdomyosarcoma. These include genetic conditions such as:
- Li-Fraumeni syndrome, a disorder that predisposes kids to certain types of cancer
- neurofibromatosis, a condition that causes tumors to grow on nerve tissue
- Beckwith-Wiedemann syndrome, a disorder that causes excessive growth
- Costello syndrome and Noonan syndrome, both of which are complex disorders that can cause deformities, mental retardation, and other problems
Signs and Symptoms
Symptoms generally depend on the size and location of the tumor. Sometimes a lump may be apparent on a child's body and there may be painful swelling. Other times, the tumor may be so deep within the body that it produces few if any symptoms.
When in the head, RMS may cause headaches, bulging of the eye, or a droopy eyelid. In the urinary system, it may lead to problems with urination and bowel movements, or blood in the urine or stool. If a muscle tumor is pressing on a nerve, there may be tingling or weakness in that area.
If a doctor suspects a child has RMS or another soft-tissue tumor, he or she will perform a thorough physical exam in addition to these tests:
- Imaging studies. These will likely include a CT scan, MRI, X-ray, bone scan, and ultrasound. Not only are these tests helpful in determining the size and location of the tumor, they can also help determine if cancer has metastasized.
- Biopsy. A tiny piece of cancerous tissue is removed from the body for further examination in a lab. This closer look helps doctors make a diagnosis (such as cancer) and choose the right treatment. A biopsy often be can performed laparoscopically (using a small incision and a camera to guide the doctor's movements instead of more invasive surgery).
- Blood tests. Tests such as a complete blood count, liver function panel, and blood chemistries can also give important information about how well the liver and other organs are functioning. If the doctor suspects the tumor is related to an underlying genetic condition, certain genetic tests also may be done.
- Bone marrow aspiration and biopsy. These procedures are sometimes done in patients with RMS for staging. Staging helps determine the extent of the cancer and whether it has spread to other parts of the body. Knowing the stage of the disease helps doctors decide how to treat it. Bone marrow is the spongy tissue inside bones that makes blood cells. This procedure involves removing a small amount of bone marrow tissue and examining it for cancer cells.
Treatment of RMS and other soft-tissue tumors depends on staging. The staging classification system (usually using Roman numerals I-IV) helps doctors determine how far the cancer has progressed. It takes into account things like the size of the tumor (or tumors), how deeply the tumor has penetrated an organ, and whether the tumor has spread to nearby or distant organs.
This information, in addition to other factors (like the type of tumor and the child's age and overall heath) helps doctors develop treatment plans that may include the following options, in combination or alone:
- Surgery. When the tumor is in an area that doctors can reach safely, surgery is performed to remove as much of the tumor as possible.
- Radiation. This treatment uses high-energy radiation from X-rays, gamma rays, or fast-moving subatomic particles (called particle or proton beam therapy) to target and destroy cancer cells. Besides killing cancer cells, radiation therapy also can harm normal cells, causing physical side effects like fatigue, nausea, and hair loss. Most acute side effects go away once treatment has ended. And during treatment, a child's health care team will take extensive measures to carefully monitor radiation doses to protect healthy tissue as much as possible.
- Chemotherapy. In contrast to radiation, which destroys the cancerous cells of a tumor in a specific area of the body, chemotherapy works to treat cancer throughout the body. Often, several chemotherapy drugs are combined to attack the cancer cells in different ways. Like radiation, side effects are likely but will ease once treatment ends.
Being told that a child has cancer can be a terrifying experience, and the stress of cancer treatment can be overwhelming for any family.
Although you might feel like it at times, you're not alone. To find out about support that may be available to you or your child, talk to your doctor, a hospital social worker, or child life specialist. Many resources are available that can help you get through this difficult time.
Reviewed by: Andrew W. Walter, MD
Date reviewed: March 2013
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