Fibrosarcoma

Definition

Fibrosarcoma is a malignant tumor that arises from fibroblasts (cells that produce connective tissue). This is a type of sarcoma that is predominantly found in the area around bones or in soft tissue.

Description

Fibrosarcomas are the result of fibroblasts, which produce connective tissue such as collagen. Fibrosarcoma tumors are consequently rich in collagen fibers. The immature, proliferating fibroblasts take on an interlacing, or herringbone, pattern.

Fibrosarcomas can form from fibroblasts in soft tissue such as muscles, connective tissues, blood vessels, joints, and fat. Soft tissue fibrosarcoma normally occurs in fibrous tissue of the body's trunk and the extremities such as the arms and legs. Soft tissue fibrosarcomas are extremely rare, with approximately 500 new cases reported each year.

Sarcomas of the bone

Fibrosarcoma can also occur in bones. While a bone is made up of inorganic molecules such as calcium phosphate, it also has an organic element made up of 95% collagen, similar to the collagen found in the skin. Fibrosarcomas of the bone usually occur in long bones in the bone marrow cavity where collagen is formed. The bones that predominantly yield fibrosarcomas are those in the legs, arms, pelvis, and hip.

Sarcomas of the bone are rare and represent about 0.2 percent of all new cancer cases each year. The two most common forms of bone cancer are osteosarcoma and Ewing's sarcoma. Among the less common are chondrosarcoma, fibrosarcoma, and malignant fibrous histiocytoma, all of which arise from spindle cell neoplasms.

Demographics

Fibrosarcomas typically develop in people between the ages of 25-79. The peak age of occurrence is 55-69 years. Generally, fibrosarcomas develop equally in men and women, though they are rare in children.

Infantile fibrosarcoma, also known as congenital fibrosarcoma or juvenile fibrosarcoma, is unique. Under microscopic examination, it is similar to fibrosarcomas seen in adults. However, infantile fibrosarcomas have a more positive prognosis with a post-treatment, five-year survival rate of 83% to 94%.

Causes and symptoms

Fibrosarcomas of the bone are sometimes connected with underlying benign bone tumors. Both fibrosarcomas of soft tissue and of the bone can develop as a result of exposure to radiation. This can result as a side effect from previous radiation therapy for unrelated primary cancer treatment. Individuals with other bone diseases, such as Paget's disease and osteomyelitis, are at a higher risk for developing fibrosarcomas.

There are many symptoms associated with the onset of fibrosarcomas. The following is a list of the main symptoms that may be present:

• pain

• swelling

• firm lump just under the skin or on a bone

• broken bone

• impeded normal range of motion

• neurologic symptoms

• gastrointestinal bleeding (seen in soft tissue abdominal fibrosarcomas)

• urinary frequency (seen in pelvic fibrosarcomas)

• urinary obstruction (seen in pelvic fibrosarcomas)

Diagnosis

In order to diagnose fibrosarcoma, a doctor will take the patient's medical history and will conduct a thorough physical exam. Blood tests will be performed to rule out other conditions and to identify cancer markers.

The most revealing initial exam is an x ray. It can show the location, size, and shape of the tumor. If a malignant tumor is present, the x ray will expose a soft tissue mass with ill-defined edges. This procedure takes less than an hour and can be performed in the doctor's office.

Once there is evidence of a tumor, one or more of several other procedures may be performed, including computed tomography (CT) scans, magnetic resonance imaging (MRI), angiograms, and biopsies.

Treatment team

The patient's primary care physician may perform the initial diagnostic tests. However, in order to comprehensively diagnose and treat fibrosarcomas, the primary care physician will refer the patient to an oncologist (cancer specialist). Radiologists, pathologists, and surgeons will also be involved to read x rays, examine tissue samples, and, if needed, remove the tumor.

Other individuals might be involved with the treatment of fibrosarcoma, including nurses, dieticians, and physical or vocational therapists.

Clinical staging, treatments, and prognosis

After the physician makes the diagnosis, it is important to determine the stage of the cancer. This will help reveal how far the cancer has progressed and how much tissue has been affected.

The American Joint Committee on Cancer developed the most widely used staging system for fibrosarcomas. The foremost categories of this system include grade (G), size of the tumor (T), lymph node involvement (N), and presence of metastases (M). Low grade and high grade are designated G1 and G3, respectively. The size of the tumor can be less than 5 centimeters (2 inches), designated as T1, or greater than 5 centimeters, designated as T2. If the lymph nodes are involved, N1 is designated, while no lymph involvement is designated N0. Finally, there may be a presence of distant metastases (M1), or no metastases (M0). The following is a list of stages and their indications:

• Stage IA: (G1, T1, N0, M0)

• Stage IB: (G1, T2, N0, M0)

• Stage IIA: (G2, T1, N0, M0)

• Stage IIB: (G2, T2, N0, M0)

• Stage IIIA: (G3, T1, N0, M0)

• Stage IIIB: (G3, T2, N0, M0)

• Stage IVA: (Any G, any T, N1, M0)

• Stage IVB: (Any G, any T, N1, M1)

Tumors with lower stage numbers, such as IA and IB, contain cells that look very similar to normal cells, while tumors with higher stage designations are composed of cells that appear very different from normal cells. In higher staged tumors, the cells appear undifferentiated.

Physicians can employ several courses of treatment to remove fibrosarcomas. The most effective treatment is surgical removal; this is used as a primary treatment for all stages of fibrosarcoma. When performing the surgery, the surgeon will remove the tumor and some healthy soft tissue or bone around it to ensure that the tumor does not recur near the original site.

Prior to surgery, large tumors (greater than 5 centimeters, or 2 inches) may be treated with chemotherapy or radiation in order to shrink them, thus rendering the surgical procedure more effective.

Even individuals with low-grade fibrosarcoma who have undergone surgery experience a moderate risk of local recurrence. To combat recurrence, adjuvant chemotherapy (the use of one or more cancer-killing drugs) and radiation therapy (the use of high-energy rays), such as irradiation and brachytherapy, are also used to complement surgery. Employing chemotherapy or radiation therapy individually without surgery is much less effective.

After therapy, low-stage fibrosarcomas (stages IA and IB) have greater five-year survival rates than high stages (Stages IVA and IVB). Because high-grade tumors are more aggressive and more highly metastatic than lower grade tumors, patients with high-grade tumors have a lower survival rate. Not only is the grade of the tumor (the estimate of its aggressiveness) important in determining prognosis, the age of the patient is also crucial. Generally, fibrosarcomas that occur in childhood and infancy have a lower mortality rate than those that occur in adults. Additionally, patients with fibrosarcomas that occur in the extremities have a better survival rate than those with fibrosarcomas in the visceral region.

Metastases appear later in the development of fibrosarcomas. The lungs are the primary sites of metastasis for fibrosarcomas that develop in the extremities. Once metastasis to the lungs has occurred, the chances of survival are significantly decreased.

Alternative and complementary therapies

Many individuals choose to supplement traditional therapy with complementary methods. Often, these methods improve the tolerance of side effects and symptoms, as well as enrich the quality of life. The American Cancer Society recommends that patients talk to their doctor to ensure that the methods they choose are safely supplementing their traditional therapy. Some complementary cancer therapies include the following:

• yoga

• meditation

• religious practices and prayer

• music therapy

• art therapy

• massage therapy

• aromatherapy

Coping with cancer treatment

Chemotherapy often results in several side effects, depending on the drug used and the patient's individual tolerance. Patients may have to deal with nausea, vomiting, loss of appetite (anorexia), and hair loss (alopecia). Many times, chemotherapy as well as radiation therapy are better handled if patients are eating well. Nurses and dieticians can aid patients in choosing healthful foods to incorporate into their diet.

If the fibrosarcoma necessitated a limb amputation, then patients will need to learn how to cope with a prosthetic device. Both physical and vocational therapists can effectively help patients adjust and learn how to use the prosthetic device to perform their daily activities.

Clinical trials

Fibrosarcomas are rare, but advances are being made in both diagnostic and curative procedures. Although surgery is the most effective treatment, both pre- and post-operative adjuvant therapies are being researched to complement surgery.

Exploring the results of chemotherapy trials uncovers a trend of improved results with more intense regimens-meaning higher and more prolonged doses of drug therapy. Drugs that are being studied in 2001 include cyclophosphamide, doxorubicin, methotrexate, vincristine, dacarbazine, dactinomycin, or a combination of two or three of these.

Patients should consult with their physicians or contact the American Cancer Society to learn what procedures are currently being investigated in clinical trials. In some cases, insurance companies will not cover procedures that are part of clinical trials. Patients should talk with their doctor and insurance company to determine which procedures are covered.

Prevention

The prevention of cancer can be assisted by avoiding known chemical carcinogens such as alpha-naphthylamine, carbon tetrachloride, and benzene. Another way to avoid developing cancer is to minimize exposure to penetrating radiation such as x rays and radioactive elements. Medical x rays revolutionized the field of medicine and are used to detect and treat many diseases. In most cases, the benefits of medical x rays outweigh the risks.

Special concerns

Treatment, especially surgical amputation, can take a physical and psychological toll on cancer patients and their families. To deal with the psychological impact, there are many different support groups and psychotherapists that can help. Some therapists will consider amputation a posttraumatic stress disorder, and treat it accordingly. To deal with their condition, relying on faith practices can also be beneficial for cancer patients. Patients should discuss all options with their physician to determine what is available.

Once the cancer has been treated, patients should make sure to schedule follow-up appointments with their physicians. Physicians will want to monitor the patient for side effects or possible recurrence that may develop years after treatment.

KEY TERMS

Adjuvant

A treatment that has been added to a curative treatment to combat recurrence.

Brachytherapy

Radiotherapy that places the source of radiation close to the surface of the body or within a body cavity.

Carcinogen

An agent that is capable of causing cancer.

Epiphysis

The end of long tubular bones such as femur in the leg and the humerus in the arm.

Spindle cell

Cells shaped like a spindle, typically found in connective tissue.

Undifferentiated

Cells that have not matured normally and do not function properly.

Visceral

Having to do with an organ in the human torso.

QUESTIONS TO ASK THE DOCTOR
• What diagnostic procedures are best for the location and type of tumor suspected?

• What treatments are best for the location and type of tumor suspected?

• What kinds of side effects will this course of treatment cause?

• Are there support services available?

• What treatments are currently in clinical trials?

• What treatments will my health care insurance cover?

• What alternative treatments are safe?