- What are soft tissue sarcomas?
Sarcomas are malignant (cancerous) tumors that develop in tissues which connect,
support, or surround other structures and organs of the body. Muscles, tendons
(bands of fiber that connect muscles to bones), fibrous
tissues, fat, blood
vessels, nerves,
and synovial tissues are types of soft tissue. Soft tissue sarcomas are grouped
together because they share certain microscopic
characteristics, have similar symptoms,
and are generally treated in similar ways (1). They are
usually named for the type of tissue in which they begin.
Examples of soft tissue sarcomas and the type of tissue in which they begin
include the following (2):
- Fibrous tissue (tissue that holds bones, muscles, and
organs in place)—fibrosarcoma,
malignant
fibrous histiocytoma
- Fatty tissue—liposarcoma
- Smooth muscle (e.g., uterus)—leiomyosarcoma
- Skeletal
muscle—rhabdomyosarcoma
- Blood and lymph
vessels—epithelioid hemangioendothelioma, angiosarcoma,
lymphangiosarcoma,
Kaposi
sarcoma
- Perivascular tissue (near or around blood vessels)—glomangiosarcoma,
malignant hemangiopericytoma
- Synovial tissue (tissue that lines joints, tendon sheaths,
and fluid-filled
sacs between tendons and bones)—synovial
sarcoma
- Peripheral nerves—malignant granular cell tumor,
malignant
peripheral nerve sheath tumor (also called malignant schwannoma
or neurofibrosarcoma)
- Mesenchymal
cells (cells that develop into connective
tissue, blood vessels, and lymphatic tissue)—gastrointestinal
stromal tumor (GIST), malignant mesenchymoma
Other types of soft tissue sarcomas include alveolar soft part sarcoma, epithelioid
sarcoma, desmoplastic
small cell tumor, and clear
cell sarcoma. At this time, scientists do not know the types of tissue
in which these sarcomas begin (2). Many sarcomas have specific
chromosomal alterations, which are used to help classify the tumors (2).
Sarcomas that develop in the bone and cartilage
(osteosarcoma,
Ewing
sarcoma, and chondrosarcoma)
are not classified as soft tissue sarcomas and are not described in this resource.
(More information about these types of cancer
is available in the National
Cancer Institute (NCI) fact sheet Bone
Cancer: Questions and Answers at http://www.cancer.gov/cancertopics/factsheet/Sites-Types/bone
on the Internet.)
- Where in the body are soft tissue sarcomas more likely
to develop?
Soft tissue sarcomas can arise almost anywhere in the body. About 43 percent
occur in the extremities (e.g., arms, legs); 34 percent occur in and around
the internal organs (e.g., uterus, heart); 10 percent occur in the trunk (e.g.,
chest, back); and 13 percent occur in other locations (2).
In very rare cases, these tumors develop in the gastrointestinal
tract. A small percentage of these are GISTs. Malignant GISTs occur most
commonly in the stomach
and small
intestine.
- What are the possible causes of soft tissue sarcomas?
Although most soft tissue sarcomas do not have a clearly defined cause, researchers
have identified several factors that increase the likelihood of developing
these tumors (2). External
radiation therapy is the most well-established risk factor for soft tissue
sarcomas. Patients treated with radiation
therapy for cancers of the retina,
breast,
cervix,
ovary,
testes,
or lymphatic
system have a much higher chance of developing soft tissue sarcomas than
the general population (1). The risk appears to be related
to the dose
of radiation. To limit this risk, radiation treatment for cancer is planned
to ensure that the greatest amount of radiation is delivered to diseased tissue
while surrounding healthy tissue is protected as much as possible.
Another risk factor for soft tissue sarcomas is exposure to certain chemicals
in the workplace, including vinyl
chloride, arsenic,
herbicides
such as phenoxyacetic acids, and wood preservatives that contain chlorophenols
(2). Chronic
lymphedema
(a condition in which excess fluid collects in the tissue and causes swelling)
following radiation to, or surgical removal of, lymph
nodes is also a risk factor.
Certain inherited diseases are associated with an increased risk of developing
soft tissue sarcomas. Studies have focused on genetic
changes that may lead to the development of soft tissue sarcomas. For example,
people with Li-Fraumeni
syndrome (associated with alterations in the p53
tumor
suppressor gene), von Recklinghausen disease (also called neurofibromatosis
type 1 and associated with alterations in the NF1 gene),
hereditary
leiomyomatosis and renal cell cancer syndrome (with alterations in the
FH gene), and hereditary
retinoblastoma
(with alterations in the RB1 gene) are at increased risk of developing soft
tissue sarcomas.
Kaposi sarcoma is a soft tissue sarcoma that sometimes develops in people
with human
immunodeficiency virus (HIV) infection.
The primary cause of Kaposi sarcoma is infection with Kaposi
sarcoma-associated herpesvirus (KSHV), or human
herpesvirus 8. However, people infected with KSHV, but not HIV, rarely
develop Kaposi sarcoma (3).
- How often do soft tissue sarcomas occur?
Soft tissue sarcomas are rare. About 9,500 new cases were diagnosed
in the United States in 2006 (4), which is less than 1 percent
of all new cancer cases. However, sarcomas occur more often in children and
young adults. For example, soft tissue sarcomas account for about 7 percent
of all childhood cancers. The most common soft tissue sarcomas are leiomyosarcoma,
malignant fibrous histiocytoma, and liposarcoma. By site of origin, leiomyosarcoma
is the most common sarcoma of the organs, while liposarcoma and malignant
fibrous histiocytoma are the most common sarcomas of the extremities (5).
Rhabdomyosarcoma is the most common soft tissue sarcoma in children.
- What are the symptoms of soft tissue sarcomas?
Soft tissue sarcomas usually appear as a lump or mass, but they rarely cause
pain, swelling, or other symptoms (1). A lump or mass might
not be a sarcoma; it could be benign
(noncancerous), a different type of cancer, or another problem. It is important
to see a doctor about any physical change, such as a lump or mass, because
only a doctor can make a diagnosis.
- How are soft tissue sarcomas diagnosed?
The doctor performs a physical
exam and may use the following procedures and tests to diagnose soft tissue
sarcoma:
- X-rays
create images of areas inside the body on film.
- Computed
tomography (CT), a procedure that uses special x-ray equipment
to obtain cross-sectional pictures of the body, can determine whether a
soft tissue tumor has metastasized
(spread) to the lung
or abdomen
(1). CT scans, also called CAT scans, can also be helpful
in determining the size of the tumor and whether the tumor can be accessed
through surgery.
- Magnetic
resonance imaging (MRI) uses a powerful magnet linked to a
computer to create detailed pictures of areas inside the body. MRI scans
can aid in diagnosis, particularly in helping to distinguish soft tissue
sarcomas from benign tumors, as well as showing the extent of the tumor.
MRIs are also used to monitor the patient after treatment to see if the
tumor has recurred
(come back) (1).
- A biopsy
is the removal of cells or tissue for examination by a pathologist.
The pathologist studies tissue samples under a microscope or performs other
tests on the cells or tissue. A biopsy is the only sure way to tell whether
a person has cancer.
Specialized testing of the tumor cells for chromosomal alterations may also
be conducted to aid in diagnosis (5).
- How are soft tissue sarcomas treated?
Treatment for soft tissue sarcomas is determined mainly by the stage
of the disease. The stage depends on the size of the tumor, the grade,
and whether the cancer has spread to the lymph nodes or other parts of the
body. The most important component of the stage is the tumor grade (how abnormal
the cancer cells look under a microscope and how quickly the tumor is likely
to grow and spread). Treatment options for soft tissue sarcomas include surgery,
radiation therapy, and chemotherapy.
A multidisciplinary
team of cancer specialists can help plan the best treatment for patients with
soft tissue sarcomas.
- Surgery is the usual treatment for soft tissue sarcomas.
For surgery to be effective, the surgeon
must remove the entire tumor with negative margins (no cancer cells are
found at the edge or border of the tissue removed during surgery). The surgeon
may use special surgical techniques to minimize the amount of healthy tissue
removed with the tumor. Some patients need reconstructive
surgery.
- Radiation therapy, also called radiotherapy, involves
the use of high-energy x-rays to kill cancer cells. This therapy may be
used before surgery to shrink the tumor, after surgery to kill any cancer
cells that may remain in the body, or both before and after surgery. Radiation
may come from a machine outside the body (external radiation therapy). It
can also come from radioactive
materials placed directly into or near the area where the cancer cells are
found (internal
radiation therapy or radiation implant)
(1).
- Chemotherapy is the use of anticancer drugs
to kill cancer cells. Chemotherapy may be used before or after surgery,
and with or without radiation therapy. The effectiveness of current anticancer
drugs depends on the type of sarcoma. Some sarcomas are very responsive
to chemotherapy, while others do not respond to current anticancer drugs
(1). Some sarcomas with specific chromosomal alterations
can be treated with therapies targeted to the alteration.
For example, imatinib
mesylate (Gleevec®)
is a targeted
therapy used to treat GIST that has metastasized (1).
- Are clinical trials (research studies) available? Where
can people get more information about clinical trials?
Yes. Participation in clinical trials is an important treatment option for
many people with soft tissue sarcomas. To develop new treatments, and better
ways to use current treatments, the NCI, a component of the National
Institutes of Health, is sponsoring clinical trials in many hospitals
and cancer centers around the country. Clinical trials are a critical step
in the development of new methods of treatment. Before any new treatment can
be recommended for general use, doctors conduct clinical trials to find out
whether the treatment is safe for patients and effective against the disease.
People interested in taking part in a clinical trial should talk with their
doctor. Information about clinical trials is available from the NCI's Cancer
Information Service (CIS) (see below) at 1–800–4–CANCER
and in the NCI booklet Taking Part in Cancer Treatment Research Studies,
which can be found at http://www.cancer.gov/publications
on the Internet . This booklet describes how research studies are carried
out and explains their possible benefits and risks. Further information about
clinical trials is available at http://www.cancer.gov/clinicaltrials
on the NCI's Web site. The Web site offers detailed information about specific
ongoing studies by linking to PDQ®,
the NCI's comprehensive cancer information database. The CIS also provides
information from PDQ.
