Sarcoma: About Sarcoma

Sarcoma (from the Greek word for fleshy tumor), is an uncommon type of cancer that originates in connective tissues such as bone, cartilage and muscle. It develops when the cells that make up these tissues (called mesenchymal cells) begin to grow out of control.

Some types of sarcoma are found in children, while others attack men and women in their most productive years (30-60).

Most cancers are classified as carcinomas, which start in organs such as the lungs, breast, colon, or others. Carcinomas can be spread through the lymphatic system or blood to other areas of the body. Sarcomas are different, as they rarely spread to the lymph glands. Rather they mostly travel through the blood stream and may eventually spread to the liver, lungs, and, rarely, the brain.

While sarcomas may arise anywhere in the body, they most often originate in the arms, legs, chest, or in the abdomen. Sarcomas are often not symptomatic until they are very large and may first be noticed as swelling or a painless lump. As they grow larger they can cause pain or soreness by pressing on surrounding nerves or muscles and eventually spreading to nearby organs. As yet, no one knows why some people develop these growths and others don’t.

Curing sarcoma usually depends upon discovering the tumor at an early stage. Because sarcomas represent less than one percent of all cancers and are seldom seen by most oncologists, finding the best care can be challenging. Proper management of sarcomas requires evaluation at a Comprehensive Cancer Center, because it is essential to start with an accurate diagnosis, which is mostly likely to come from a pathologist who frequently sees this rare disease.

Once the correct diagnosis is made, treatment by a multidisciplinary team of medical, surgical and radiation oncologists skilled in all aspects of its clinical care is strongly recommended for this uncommon disease. In addition, this approach may provide further treatment options through access to the latest investigational therapies.

Risk Factors

The American Cancer Society estimates that about 3,000 new bone sarcomas, and 12,000 new soft tissue sarcomas (STS) will be diagnosed in the coming year. 

These rare tumors represent only one percent of all adult cancer and about 15 percent of all cancers in children.

Other risk factors may include:

Previous radiation

Radiation exposure (for the prior treatment of other cancers) may increase the likelihood of developing sarcoma. However this accounts for fewer than 5 percent of all sarcomas. Recent advances in radiation therapy now allow physicians to target cancers much more precisely and to limit radiation doses, which may minimize these risks.

Genetic factors                                                                                                                              

Some inherited conditions may increase an individual’s chance of developing sarcoma. These include

  • Neurofibromatosis
  • Gardner’s syndome
  • Li-Fraumeni syndrome
  • Retinoblastoma
  • Werner’s syndrome  
  • Gorlin syndrome
  • Tuberous sclerosis
  • Marfucci syndrome
  • Oillier disease

It is important to note that many people who develop sarcomas have no identifiable risk factors.

 

Symptoms

Sarcomas can easily shove aside normal tissue without causing any symptoms. Discomfort may occur only once these tumors grow large enough to press against the nerves or muscles.

A bone sarcoma may cause pain and/or swelling in an arm or leg, the trunk, the pelvis, or the back. This area may sometimes feel warm to the touch. Other symptoms include a limited range of motion in a joint, a fever for no known reason or a bone that breaks from no apparent outward injury.

A soft issue sarcoma may cause pain or a feeling of fullness or difficulty breathing.

These symptoms are very general and may also be signs of other medical conditions. 

Patients are naturally concerned when finding a lump in the arm, leg, or trunk of the body yet it is important to remember that most lumps are not sarcomas.  A lipoma, for example, is a very common benign growth—made of fat cells, not cancer cells.   It is important to have any lump or swelling immediately evaluated by a physician.

Diagnosis

Often a sarcoma is discovered only after it has grown quite large.  A second difficulty is that the physician who first evaluates the patient usually has little or no experience in treating this type of cancer.   It is crucial that a multidisciplinary team familiar with the many different types of sarcoma is consulted early on. 

After a physical exam and history, the patient may undergo any of the following diagnostic tests:

  • X-ray:  A physician may first order a regular x-ray of the area where the lump has been found.  In some cases, a chest x-ray is ordered to see if sarcoma has spread to the lungs.
  • Computed Tomography (CT) scan: CT scans take many different x-rays to produce detailed, cross-sectional images of your body. A CT scan is often done if the doctor suspects a soft tissue sarcoma in the chest, abdomen, or behind the abdominal cavity. In some cases a CT scan is ordered to see if the sarcoma has spread into the lungs, liver or other organs.
  • Magnetic resonance imaging (MRI): MRI scans use radio waves and strong magnets instead of x-rays to take pictures of the body. MRIs are often better than CT scans in evaluating sarcomas in the arms or legs. They map the location, size, and sometimes even the type of tissue contained in the tumor, and are useful tools for planning biopsies.
  • Fine-needle biopsy: After numbing the area, a physician inserts a needle into the bone or soft tissue to extract a sample for analysis. The cells from that sample are then examined under a microscope. Most needle biopsies are performed by radiologists who use x-rays or a CT scan to guide the placement of the needle.
  • Surgical Biopsy: Sometimes, the size or location of the mass requires a biopsy.  An incisional biopsy removes a small part of a large tumor. An excisional biopsy removes the entire tumor.  When the growth is close to the surface, this operation may be performed using local anesthesia (the patient is awake, and only a portion of the body is numbed.)  When the tumor is within the chest of abdomen, general anesthesia (putting the patient to sleep) is used.

Laboratory tests may include:

  • Immunohistochemistry studies:  A pathologist (one who studies the origin of disease) treats the patient’s tissue sample with certain chemicals that change color, indicating whether a sarcoma is present, and if so, what type.
  • Cytogenetic analysis: This test looks for changes in the patient’s genetic blueprint.  It involves growing cancer cells in a lab for several days, then examining them under a microscope for any changes.  In certain kinds of sarcoma, part of one chromosome abnormally attaches to another, a process called translocation.
  • Fluorescent in situ hybridization (FISH): This test looks for translocations and other chromosome changes.
  • Reverse transcription polymerase chain reaction (RT-PCR): This test is used to confirm the type of tumor present and provides a chemical analysis of the RNA (a substance that is made from DNA) in genes that are affected by translocation.
  • Gene profiling: The genetic profile of a cancer is determined through molecular testing. More and more frequently it is important to know if gene mutations exists in a cancer.  These gene mutations, such as c-kit observed in patients with GIST, can present opportunities for specific or “personalized” drug therapy.   

Sarcoma Staging

Grading the tumor

Sarcomas are graded on a scale of 1-6. A low-grade tumor is generally easier to treat than a high-grade or more aggressive tumor.  In order to determine the grade, physicians must perform a biopsy, which allows them  to determine the type of tumor, its rate of growth and how much of it is comprised of dead or dying tissue.

Sarcomas that have more normal cells and fewer dividing cells are called low-grade because they tend to be slow growing and take longer to spread.   Once the sarcoma has been graded, the grade is considered when determining its stage.

Further information on how sarcomas are graded can be found here: http://www.cancer.org/cancer/sarcoma-adultsofttissuecancer/detailedguide/sarcoma-adult-soft-tissue-cancer-staging

Staging the tumor

The staging system for soft-tissue sarcoma is defined as follows:

Stage IA

The tumor is smaller than 5 cm (2 inches) across and has not spread to lymph nodes or more distant sites. The cancer is grade 1 or the grade cannot be determined.

Stage IB

The tumor is larger than 5 cm (2 inches) across and has not spread to lymph nodes or more distant sites. The cancer is grade 1 or the grade cannot be determined,

Stage IIA

The tumor is smaller than 5 cm (2 inches) across. It has not spread to lymph nodes or more distant sites. The cancer is grade 2 or 3.

Stage IIB

The tumor is larger than 5 cm (2 inches) across and has not spread to lymph nodes or more distant sites. The cancer is grade 2.

Stage III

The tumor is larger than 5 cm (2 inches) across and has not spread to lymph nodes or more distant sites. The cancer is grade 3.

OR:  The tumor of any size and any grade has spread to nearby lymph nodes but not to distant sites.

Stage IV

The cancer, of any size and any grade, has spread to lymph nodes near the tumor and/or to distant sites.