Sarcoma, Soft Tissue: Introduction

Approved by the Cancer.Net Editorial Board, 05/2016

ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Soft-Tissue Sarcoma. To see other pages, use the menu. Think of that menu as a roadmap to this full guide.

Cancer begins when healthy cells change and grow out of control, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.

About sarcoma

Sarcoma can start in any part of the body, such as the bone or soft tissue.

  • 50% begin in an arm or leg

  • 40% start in the torso or abdomen

  • 10% occur in the head or neck

Both children and adults can develop a sarcoma. It is rare in adults, accounting for about 1% of all adult cancers. However, sarcomas are more common in children, representing about 15% of all childhood cancers.

This section covers sarcoma of the soft tissues. Learn more about sarcoma that starts in a bone.

About soft-tissue sarcoma

Soft-tissue sarcoma (STS) is a group of cancers that begin in the connective tissues that support and connect the body, including:

  • Blood vessels

  • Fat cells

  • Lining of joints

  • Lymph vessels

  • Muscle

  • Nerves

  • Tendons

As a result, STS can occur almost anywhere in the body. When an STS begins and is small, it can go unnoticed because it usually does not cause problems. However, as an STS grows, it can interfere with the body's normal functions.

Because there are at least 50 different types of STS, it is more accurate to describe them as a family of related diseases, rather than as a single disease. Specific types of sarcoma are often named according to the normal tissue cells they most closely resemble, as listed below. This is different from most other types of cancer, which usually are named for the part of the body where the cancer began. Some sarcomas do not look like any type of normal tissue and are thought to come from stem cells or other primitive cells. Stem cells are special cells that can mature into specific tissues or organs.

The list below describes several common types of STS and related connective tissue tumors.

Name of Sarcoma

Related Normal Tissue Type

Angiosarcoma

Blood or lymph vessels

Desmoid tumor, also called deep fibromatosis

Fibroblasts, which are the most common type of cells in connective tissue

Ewing family of tumors

No obvious related normal tissue; may be a tumor of stem cells

Fibrosarcoma

Fibroblasts, which are the most common type of cells in connective tissue

Gastrointestinal stromal tumor (GIST)

Specialized neuromuscular cells of the digestive tract

Kaposi sarcoma

Blood vessels

Leiomyosarcoma

Smooth muscle

Liposarcoma

Fat tissue

Myxofibrosarcoma

Connective tissue

Malignant peripheral nerve sheath tumor (MPNST), also known as neurofibrosarcoma

Cells that wrap around nerve endings, similar to the way insulation wraps around a wire

Rhabdomyosarcoma

Skeletal muscle

Synovial sarcoma

No obvious related normal tissue; may be a tumor of stem cells

Undifferentiated pleomorphic sarcoma (UPS), often referred to as malignant fibrous histiocytoma (MFH) in the past

No obvious related normal tissue; may be a tumor of stem cells or a distant relative of rhabdomyosarcoma

Expert pathologists have described and classified many types and subtypes of sarcomas. A pathologist is a doctor who uses a microscope to look at the tumor specimen to make the diagnosis. Pathologists are looking for new ways to quickly determine a tumor's subtype because this helps to understand the prognosis and to decide the treatment plan. Looking at a tumor's abnormal genetics may help determine its characteristics and predict which treatments will be most effective. The use of targeted therapy has resulted in major advances in treating several types of sarcoma, including GIST, dermatofibrosarcoma protuberans (DFSP), tenosynovial giant cell tumor, and desmoid tumors. 

Pathologists also describe sarcoma by its “grade,” which describes how much cancer cells look like healthy cells when viewed under a microscope. The grade can help the doctor predict how quickly the sarcoma will grow and spread. In general, the lower the tumor’s grade, the better the prognosis, which refers to the chance of successful treatment and outcome. Learn more about grade in the Stages and Grades section.

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If you would like more of an introduction, explore these related items. Please note that these links will take you to other sections on Cancer.Net:

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