What is sarcoma?
A sarcoma is a type of tumor that develops in connective tissue, such as bone, cartilage or muscle. Malignant sarcoma are very rare (1% of all adult malignancies and about 15% of childhood malignancies). Approximately 14,000 to 15,000 sarcomas are diagnosed in the United States every year (3,000 bone sarcomas and 11,000 to 12,000 soft tissue sarcomas).
Sarcomas appear in the body in the following percentages:
- 40% occur in the lower extremities;
- 15% in the upper extremities;
- 30% in the trunk/chest wall/abdominal locations;
- 15% in the head and neck region.
Conditions that can be mistaken for tumors
Many conditions can be mistaken for tumors. Everyone has occasional lumps and bumps, and it is important to be able to tell the difference between those masses that might be cancerous and those that occur because of injury, congenital growths or the normal aging process. For instance, in the skeleton, stress fractures, chronic infections and benign bone tumors might appear to be malignant.
What are the types of sarcoma?
Benign bone tumors
Benign (noncancerous) tumors are even more common than malignant tumors in the musculoskeletal system.
Common types of benign tumors include:
- Aneurysmal bone cysts.
- Simple bone cysts.
- Fibrous dysplasia.
- Langerhans Cell Histiocytosis.
- Non-ossifying fibromas.
In addition, benign bone tumors can be associated with familial conditions or syndromes, such as MHE (multiple hereditary exostosis), Ollier’s Disease, Maffucci’s Disease or McCune-Albright syndrome.
Benign bone tumors that are more aggressive, such as giant cell tumor or chondromyxoid fibromas, usually require surgery. In these cases, techniques such as synthetic bone graft substitutes are used to rebuild rather than remove bone. Drugs such as denosumab or doxycycline are also used to treat specific tumors.
Malignant bone tumors
Though bone tumors are a rare type of cancer (approximately 3,000 cases a year in the United States), there are many different types.
Common types of malignant bone tumors include:
More than one-third of bone sarcomas are diagnosed in patients under the age of 35 years old; many are diagnosed in children.
Metastatic bone tumors
As opposed to primary bone sarcoma (cancer that starts in the bone), metastatic bone cancer starts in another location (such as an organ) and travels to the bone. This cancer comes in many forms, most often thyroid, lung, kidney, breast or prostate.
When a cancer from a distant organ spreads to the skeleton, it can create structural problems in the bone that may lead to greater pain and reduced functioning.
Soft Tissue Tumors
Benign soft tissue tumors
Benign soft tissue tumors are very common (fewer than 5% of all lumps or bumps discovered are cancerous). Many of these tumors can be monitored regularly, but some have to be removed by surgery. Some benign tumors, such as desmoid tumors, may require treatment from the medical oncology, radiation oncology or interventional radiology teams, all of which work closely together.
The most common types of benign soft tissue tumors include:
- Desmoid tumors.
- Large arteriovenous malformations.
- Lipomas (fatty tumors).
- Pigmented villonodular synovitis.
- Synovial chondromatosis.
Malignant soft tissue tumors
Soft tissue sarcomas begin in the muscle or other connective tissues of the body. Unlike bone tumors, most soft tissue sarcomas occur in adults, though certain types, such as rhabdomyosarcoma, are found mostly in children.
Some of the most common types of soft tissue sarcomas include:
- Desmoplastic small round cell tumors.
- Gastrointestinal stromal tumor (GIST).
- Malignant peripheral nerve sheath tumor.
- Synovial sarcoma.
- Undifferentiated pleomorphic sarcoma.
Genitourinary sarcomas are rare cancerous (malignant) tumors that develop in the genitals or urinary tract. Genitourinary sarcomas are less than 5% of all types of sarcomas, and they tend to develop more in children than in adults. They typically develop in:
- The bladder
- The kidney
- The ureters (the tubes that drain urine from the kidneys into the bladder)
- The urethra (the tube that drains urine from the bladder to outside of the body)
- The male reproductive system (prostate, testicles, and penis)
- The vagina
In general, there are 14,000 new cases of sarcomas diagnosed in the United States each year. No study has shown how many of these cases affect the genitourinary system. However, bladder sarcomas are the most common type of genitourinary sarcomas.
Bladder sarcomas tend to form in the area between the openings of the ureters and the urethra. But they can also develop in the entire bladder area.
As with all other types of sarcomas, the causes of genitourinary sarcomas are unclear. The following factors may put you at a higher risk for developing sarcomas in general:
- Exposure to certain chemicals, such as phenoxyacetic acid in herbicides and chlorophenols in wood preservatives
- Exposure to higher doses of radiation
- Long-term bladder infections
- Taking certain kinds of pain medicines for a long time
- Certain inherited disorders and chromosome mutations, such as Hippel-Lindau syndrome and neurofibromatosis
There are no clear symptoms associated with genitourinary sarcomas in the early stages. However, you can feel a painless mass by touch. As the mass grows bigger and presses against the nearby nerves, you will start to feel some pain or soreness.
Symptoms of larger genitourinary sarcomas include:
- Blood in urine (hematuria) or trouble urinating
- Sores, discharge, or skin changes in the genital-urinary area
Of all genitourinary sarcomas types, bladder sarcomas tend to fare better with treatment. The presence of blood in the urine makes the early detection of bladder sarcomas possible. The overall survival rate for a patient with any sarcoma depends on the type, location, size, and stage of the tumor.
Symptoms and Causes
What are the symptoms of sarcoma?
The symptoms of sarcomas vary. For example, in their early stages, some sarcomas may not cause noticeable symptoms. Sarcomas may appear as a painless lump under the skin. Other sarcomas may form in the abdomen, and may not cause symptoms until they grow very large and press on an organ.
Other sarcomas can present as long-lasting bone pain or swelling in an arm or leg that gets worse at night, or decreased mobility.
Sarcoma symptoms that should be investigated are masses (growths) that grow larger, painless masses that have become painful or masses larger than a golf ball (around five centimeters).
In the case of children, a child who has bone pain that does not get better on its own, and that did not occur with an injury, should have an imaging test to investigate.
Diagnosis and Tests
How is sarcoma diagnosed?
Diagnosis of sarcoma can be challenging. Often, special tests are performed on a tissue sample to understand the exact type of sarcoma, as there are more than 50 known subtypes of sarcoma— many of which can require specific treatment variations.
To diagnose a sarcoma, the doctor will begin with a thorough history and physical examination. The doctor might also use certain tests when making the diagnosis. These include:
- X-ray: An X-ray will be taken to look for abnormal growths on the bones.
- Computed tomography (CT): CT uses computers to combine many X-ray images into cross-sectional views of the inside of the body.
- Magnetic resonance imaging (MRI): MRI uses large magnet, radio waves and a computer to create clear images of the body. This may be ordered for clearer pictures if an X-ray is not normal.
- Bone scan: This test uses a small amount of radioactive material injected into the body to identify bone disorders, such as cancer.
- PET scan: This test uses a special glucose tracer that is concentrated in cancer cells, and shows the areas in the body where the glucose is higher than normal, suggesting the presence of a rapidly growing tumor.
- Biopsy: This is a procedure in which a piece of tissue from the affected area is removed so that it can be studied for cancer cells under a microscope.
What are the stages of sarcoma?
One of the biggest concerns about a cancer diagnosis is whether the cancer has metastasized (spread) beyond its original location. To determine this, the doctor assigns a number (1 through 4) to your diagnosis. The higher the number, the more the cancer has spread throughout your body. This is called "staging." The doctor needs this information in order to plan your treatment.
The following staging criteria apply to bone and soft tissue sarcoma only.
Soft tissue sarcoma stages:
- Stage 1: Stage 1 is divided into stages 1A (smaller than five centimeters) and 1B (larger than five centimeters).
- Stage 2: Stage 2 is divided into stages 2A (smaller than five centimeters) and 2B (larger than five centimeters) for soft tissue sarcomas of the head and neck, extremities (arms and legs), gastrointestinal tract and retroperitoneum (the part of the body behind the abdomen).
- Stage 3: Stage 3 is divided into 3A or 3B based on the size of the tumor, the lymph node involvement or grade (based on the type of soft tissue sarcoma).
- Stage 4 (metastatic): The tumor has spread to the lymph nodes in the extremities or to other parts of the body (for example, the lungs).
Bone sarcoma stages:
- Stage 1: Stage 1 is divided into stages 1A (smaller than eight centimeters) and 1B (larger than eight centimeters).
- Stage 2: Stage 2 is divided into stages 2A (smaller than eight centimeters) and 2B (larger than eight centimeters) for sarcomas of the head and neck, extremities (arms and legs), gastrointestinal tract and retroperitoneum (the part of the body behind the abdomen).
- Stage 3: Stage 3 is divided into 3A or 3B based on the size of the tumor, the lymph node involvement or grade (based on the type of bone sarcoma).
- Stage 4 (metastatic): The tumor has spread to the lymph nodes in the extremities or to other parts of the body
(for example, the lungs).
Management and Treatment
How are sarcomas treated?
Sarcomas are treated by specialists, depending on where the sarcoma is located. In larger medical centers, sarcomas are treated by a team of caregivers, including surgeons, radiologists, medical oncologists (cancer specialists), radiation oncologists, pathologists, pediatric specialists (for cancers in children), psychologists and social workers.
The most common forms of treatment for sarcoma are surgery, radiation and chemotherapy.
Most tumors are removed by surgery. This treatment is often combined with radiation therapy to help prevent the sarcoma from returning.
In removing a tumor with surgery, the goal is to minimize the risks of a sarcoma returning in the same location or spreading. In order to do this, the surgeon will remove the tumor with a wide local excision, while leaving a margin of healthy (“negative”) tissue at the edges — meaning all the tumor is removed without leaving any obvious or microscopic disease. The goal is to preserve as much normal anatomy as possible. Sometimes, artificial implants or bone taken from another part of the body or donor tissue can be used to replace the bone that was removed during surgery.
While removing the tumor completely is vital, rebuilding the area is just as important. Limb salvage (saving/preserving an arm or a leg) in complex tumor situations can come in many forms, and includes such techniques as using metal replacements for joint reconstruction, donor bone to reconstruct bone defects, or even bone taken from another part of the body to replace the bone that was removed during surgery.
Despite increasing abilities to perform limb salvage, sometimes the safest or best option is to amputate the affected limb, which can be a very difficult decision.
Radiation therapy is a form of cancer treatment that uses high energy X-rays to kill cancer cells while minimizing damage to healthy cells. Radiation therapy can either be internal (placed in the body) or external (delivered by a machine outside the body). High-dose radiation is delivered to the areas at risk, while doses to normal tissues are minimized in order to reduce the risk of side effects.
In certain cases that have not spread, another kind of radiation, called brachytherapy, can be used. Brachytherapy can be delivered in two ways: intra-operative radiotherapy (during surgery), and interstitial brachytherapy, which is delivered through a series of catheters (plastic tubes) after surgery. Radiation can also be used for patients with sarcoma that has spread (metastatic disease).
Side effects of radiation therapy include:
- Nausea and vomiting.
- Changes to the skin.
- Irritation of the bladder.
- Edema (swelling) in the legs.
Chemotherapy is the use of medications to kill or to slow the growth of rapidly multiplying cancer cells. These medications are often given intravenously (through a needle into a blood vessel) and can have major side effects. Chemotherapy is often given before surgery to shrink the tumor.
Side effects of chemotherapy include:
- Nausea and vomiting.
- Hair loss.
- Loss of appetite.
- Low blood count.
- Mouth sores.
Sometimes benign bone tumors (e.g., osteoid osteoma) or sarcomas can be heated or frozen to destroy the mass. An interventional radiologist does this procedure using guided imaging (for example, placing the probe to freeze tissue using a CT scan).