Sarcomas are a group of rare cancers that most commonly form in the soft tissues (soft tissue sarcoma) or bones (bone sarcoma) (see Figures 1 and 2). Sarcomas originate in tissues of the supporting structures of the body, such as muscle, tendons, connective tissues, cartilage, nerves, fat and blood vessels. As a group of cancers, they compose about 1 percent of all cancers and are, thus, considered rare. They can occur in infants to the elderly; however, more primary bone sarcomas occur in the first two decades of life (see Pediatric Sarcoma). In adults, about 1 percent of all diagnosed solid tumors are sarcoma.
Diagnosing sarcomas can be difficult. Your doctor will likely order bloodwork and imaging scans, which may include computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), ultrasound or X-rays. A biopsy, however, will often be required to confirm a sarcoma diagnosis. Types of biopsies your doctor may use include needle biopsy (tissue removed with a needle), core needle biopsy (tissue removed with wide needle), incisional biopsy (a small piece of tissue is removed) or excisional biopsy (entire lump is removed) with the procedures being carried out in a hospital operating room or in the interventional radiology department by an interventional radiologist.
Identifying the sarcoma subtype requires a pathologist to review the biopsy. A pathologist with expertise in sarcoma is highly recommended to examine the appearance of the cells under a microscope and look for cells that appear more normal or abnormal. The way the cells look will also indicate the grade of the tumor, which is used in staging (see Staging).
Molecular testing is highly recommended. The pathologist will look for specific genetic abnormalities, including chromosomes that change places, extra copies of a gene and mutations (any change in the DNA sequence of a cell). Following are some of the molecular tests your doctor may order:
- Flow cytometry
- Fluorescent in situ hybridization (FISH)
- Light and electron microscopy
Because certain types of sarcoma may respond differently to certain treatments, these test results and whether the tumor is localized (contained to one area), regional (has spread to tissues near one area) or metastatic (spread to other tissues or organs) will help your doctor recommend a personalized treatment plan for you.
Soft Tissue Sarcoma
Soft tissue sarcomas are more common than bone sarcomas. There are more than 50 types of them (see Table 1), and they can form in any of the body’s connective or supportive tissues, including blood vessels, lymph vessels, muscle, cartilage, nerves, tendons, fat, tissue around joints and fibrous tissue. Most soft tissue sarcomas begin in the arm or leg. About a third occur in the torso or abdomen, and the rest begin in the head or neck. These sarcomas are named according to where they develop in the body. For example, gastro-intestinal stromal tumors (GISTs) develop in the stroma (supportive connective tissue) of the stomach and intestines; sarcomas that develop in fat tissue are called liposarcomas (“lipo” means “fat”); and sarcomas that develop in blood vessels are called angiosarcomas (“angio” means “vessel”).
Table 1. Some Types of Soft Tissue Sarcoma
|Type of Soft Tissue Sarcoma||Tissue of Origin||Typical Age (Years)||Most Common Sites|
|Most common types|
Gastrointestinal stromal tumors
Stroma (supportive connective tissue) of the stomach and intestines
|50 and older||Wall of the stomach, small intestine|
|Leiomyosarcoma||Smooth muscle tissue||Average, 60||Uterus, small intestine or stomach|
|Liposarcoma||Fat tissue||30-60||Thigh, behind the knee, retroperitoneum (behind the abdomen)|
|Synovial sarcoma||Tissue around joints||15-35||Near the foot, ankle, hand|
Undifferentiated pleomorphic sarcoma (previously called
malignant fibrous histiocytoma)
Leg; may also develop in the retroperitoneum (behind the abdomen) or head and neck
|Alveolar rhabdomyosarcoma||Skeletal muscle||Adolescents and young adults||Large muscles of the trunk, arm, leg|
|Alveolar soft-part sarcoma||Connective tissue||Young adults||
Legs or extremities
rhabdomyosarcoma (previously called pleomorphic
|Skeletal muscle||Over age 30||Large muscles of the trunk, arm, leg|
|Angiosarcoma||Inner lining of blood vessels||60-70||Skin, breast, liver, spleen, head and neck|
|Botryoid rhabdomyosarcoma||Skeletal muscle||Average, 7||
Genital region, urinary tract
|Connective tissue that forms tendons and ligaments||10-40||
Intra-abdominal mesentery (tissue that attaches organs to the wall of the abdomen), arm, leg
Desmoplastic small round cell tumor
|Connective tissue that forms tendons and ligaments||Adolescents and young adults||Abdomen|
|Skeletal muscle||Under age 10||
Anywhere, but often in head and neck, and around the eye
Arm, hand, foot
|Fibrosarcoma||Fibrous tissue||35-55||Thigh, knee, arm, trunk|
Inner lining of blood vessels
|20-40||Soft tissues or internal organs, such as liver or lung|
Malignant peripheral nerve sheath tumors
Cells that surround a peripheral nerve (nerves that connect the central nervous system — spinal cord and brain) with other parts of the body
|20-50||Upper part of the arm and leg, trunk|
Bone sarcomas are primary cancers that originate in bone, in contrast to those cancers that spread from other organs to the bone. Primary malignant bone cancers are extremely rare and mostly occur in younger people. Following are the three most common types of primary bone sarcoma. See Table 2 for additional types.
Osteosarcoma, also called osteogenic sarcoma, is the most common bone cancer. It begins in bone cells that make new bone tissue. In children and adolescents, osteosarcoma usually develops during a growth spurt near the ends of long bones, such as in the leg (around the knee) and the upper arm. But osteosarcoma can occur in any bone, especially in older adults, and may be associated with hereditary conditions or other bony diseases.
Chondrosarcoma, the second most common primary bone cancer, develops inside the bone and is made of cartilage. Cartilage is fibrous tissue mixed with a gel-like substance, making it softer than bone but harder than most tissues in the body. It can occur anywhere cartilage is found and most frequently develops in the pelvis, legs or arms. Chondrosarcoma occurs primarily in older adults.
Ewing sarcoma, the most common tumor in the Ewing family of tumors, occurs more often in children and young adults and is extremely rare after the age of 25. It usually develops in the pelvis and legs (see Pediatric Sarcoma).
Table 2. Some Types of Bone Sarcoma
|Type of Bone Sarcoma||Tissue of Origin||Typical Age (Years)||Most Common Sites|
|Most common types|
|Chondrosarcoma||Cartilage||40 and older||Pelvis, leg, arm|
|Ewing sarcoma||Bone||10-20||Pelvis, leg|
|Osteosarcoma||Bone||10-30||Leg (near the knee), upper arm (near the shoulder)|
|Chordoma||Bone||40-70||Skull base, spine, tailbone|
|Malignant giant cell tumor of bone||Bone||20-60||Knee|
Signs of Sarcoma
Though you may experience pain or discomfort related to the sarcoma’s location and the extent of the tumor, you may not experience any symptoms at all with a bone cancer. The cancer may be found merely by the presence of a mass or even incidentally on X-rays that are taken of the area for different purposes.
As soft tissue sarcomas grow, they may put pressure on nerves, nearby organs, muscles or blood vessels, which may cause pain. A common symptom of bone sarcoma is also pain, as well as swelling around the tumor site that progressively worsens. A painful limp may develop if the tumor is in the hip, thigh, knee, leg or foot. Pain may worsen when moving or during weight-bearing activities.
Managing your pain will be important regardless of the type of sarcoma you have. Treatments often referred to as supportive or palliative care are available to control cancer-related pain (see Side Effects). The better you feel, the more likely you are to complete your treatment as planned, which offers a greater chance for a successful outcome. Talk to your doctor about the pain management options that may be appropriate for you.