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What is Sarcoma?

Last updated and reviewed on May 27, 2026.

Sarcoma is a type of cancer that starts in the body's connective tissues. Connective tissues are the parts of the body that hold everything together, like bones, muscles, fat, cartilage (the rubbery material in your joints), blood vessels, and nerves. When cells in these tissues start growing out of control, a tumor forms. That tumor is called a sarcoma.

Sarcoma is different from most other cancers. Most cancers, like breast cancer, lung cancer, or colon cancer, start in organs made of a type of tissue called epithelial tissue. Sarcomas start in a different type of tissue called mesenchymal tissue, which is the material that builds your body's framework and support structures.

How does sarcoma start

Like most cancers, sarcoma is caused by changes (called mutations) in the DNA inside cells. These mutations tell cells to grow without stopping, forming a tumor. In most cases, the reason these mutations happen is not clear. Most sarcomas are not caused by something a person did or did not do. A few things that can raise the risk of sarcoma are described in a separate guide called Risk Factors for Sarcoma.

Where Does It Start?

Because connective tissue is found all over the body, sarcoma can grow almost anywhere. The most common places include:

• The arms and legs (especially the thigh)

• The belly (abdomen) and the area behind it (called the retroperitoneum)

• The chest

• The head and neck

• The uterus (in women)

• Bones throughout the body

How does bladder cancer affect the body?

There are two broad categories: soft tissue sarcomas and bone sarcomas (like osteosarcoma).

Local effects

• Forms a lump or mass, often deep in the body (thigh, abdomen, chest)

• Causes pain as the tumor grows and presses on nearby nerves, muscles, or organs

• Can restrict movement if near a joint or limb

• May cause swelling around the affected area

How it spreads

Sarcomas most commonly spread through the bloodstream (rather than the lymphatic system, which is more typical of carcinomas). The lungs are the most frequent site of metastasis, which can cause shortness of breath, coughing, or chest pain.

Bone sarcomas specifically

• Weakened bones increase the risk of fractures

• Can cause deep, aching bone pain that often worsens at night

• May interfere with nearby joints

Systemic effects (especially in advanced stages)

• Fatigue and loss of energy

• Unintentional weight loss

• Fever or night sweats (less common)

• If near vital organs, it can impair their function

Because sarcomas are relatively rare and can grow in many different locations, symptoms vary widely depending on where the tumor is. A painless, growing lump, especially one larger than 5 cm, is generally a red flag worth evaluating.

Learn more about the signs and symptoms of bladder cancer. 

What are the two main types of sarcoma?

Doctors divide sarcomas into two main groups:

Soft Tissue Sarcomas: These grow in soft tissues like muscle, fat, nerves, tendons, and blood vessels. There are more than 70 different kinds of soft tissue sarcoma. Some of the most common include:

• Undifferentiated pleomorphic sarcoma (UPS): One of the most common soft tissue sarcomas in adults. It used to be called malignant fibrous histiocytoma (MFH).

• Liposarcoma: Grows in fat tissue, most often in the thigh or abdomen.

• Leiomyosarcoma: Grows in smooth muscle, like the muscle in the walls of the uterus, stomach, or blood vessels.

• Gastrointestinal stromal tumor (GIST): Grows in the wall of the stomach or intestines. GISTs have special gene changes that make them respond to certain targeted medicines.

• Synovial sarcoma: Often found near joints. Despite the name, it does not usually grow directly from joint tissue.

• Rhabdomyosarcoma: The most common soft tissue sarcoma in children and teens. It grows in skeletal muscle (the kind you use to move your body).

• Angiosarcoma: Grows in the blood vessel or lymph vessel walls. It can appear on the skin or in organs.

Bone Sarcomas: These grow in the bones. The main types include:

• Osteosarcoma: The most common bone cancer. It usually affects teens and young adults and most often starts near the knee or in the upper arm.

• Ewing sarcoma: Most common in children, teens, and young adults. It usually starts in the bones but can also start in soft tissue. It most often affects the pelvis, thigh, or shin.

• Chondrosarcoma: Grows in cartilage. It is most common in adults over age 40 and often develops in the pelvis, hip, or shoulder.

Genetic and inherited risk factors

There are meaningful genetic and inherited risk factors for sarcoma. While most sarcomas are sporadic (no clear hereditary cause), recent studies indicate up to 20% of sarcomas may be associated with predisposition genes, and this number will likely increase as genetic testing becomes more available. The Lancet

Here are the main inherited syndromes and genes involved:

• Li-Fraumeni Syndrome (LFS) Li-Fraumeni syndrome is a rare inherited condition caused by a mutation in the TP53 tumor suppressor gene. It dramatically raises the risk of several cancers, including sarcomas, breast cancer, leukemia, and adrenal gland tumors, often appearing in relatively young adults or even children. Sarcomas are the single most common cancer type seen in LFS families. American Cancer Society

• Hereditary Retinoblastoma (RB1) Children diagnosed with hereditary retinoblastoma, caused by a germline mutation in the RB1 tumor suppressor gene, face an increased risk for bone and soft tissue sarcomas. This predisposition is attributed to genetic susceptibility from RB1 inactivation as well as, in some cases, past radiation treatment. Sarcomas account for almost half of second primary cancers in hereditary retinoblastoma survivors. Individuals with hereditary retinoblastoma have a roughly 500-fold increased incidence of bone sarcomas, predominantly osteosarcoma. National Institute of Health

• Neurofibromatosis Type 1 (NF1) Children with NF1 develop rhabdomyosarcoma about 20 times more frequently than children without NF1, with the urogenital system being the most commonly affected site. NF1 also significantly raises the risk of malignant peripheral nerve sheath tumors (MPNSTs). PubMed Central

• Familial Adenomatous Polyposis (FAP) FAP is a genetic condition that causes the growth of adenomatous colon polyps inside the intestinal tract and is considered a risk factor for soft tissue sarcoma. It is particularly associated with desmoid tumors. City of Hope

• Ewing Sarcoma DNA Repair Genes Research has revealed that inherited variations in certain DNA damage repair genes may increase susceptibility to Ewing sarcoma. These variants display "moderate penetrance," meaning they play a substantial role in increasing risk but are most likely not sufficient to cause the disease in isolation. Dana-Farber Cancer Institute

• Other Syndromes Additional cancer predisposition syndromes linked to sarcoma include rhabdoid tumor predisposition syndrome (involving SMARCA4 and SMARCB1 genes), neurofibromatosis type 2 (NF2), and familial melanoma (CDKN2A), all with autosomal dominant inheritance. Nature

Related Cancers

Since sarcoma shares hereditary syndromes with other cancer types, those co-occurring cancers are meaningfully "related." Here's how they cluster by syndrome:

• Li-Fraumeni Syndrome (TP53 mutation) is the most sarcoma-associated syndrome

• The "core" cancers in LFS occur at particularly high frequencies and include soft tissue sarcomas, osteosarcoma, premenopausal female breast cancer, brain tumors, and adrenocortical carcinoma. Additional cancers seen at lower rates include cancers of the lung, colorectum, stomach, prostate, ovary, and pancreas, as well as leukemia, lymphoma, and melanoma. Medscape

• TP53 germline mutations are highly penetrant, with a cumulative lifetime incidence of cancer approaching nearly 100%. So if someone has a sarcoma linked to LFS, breast cancer, and brain tumors are the most important other cancers to be aware of in the family. nih

• Hereditary Retinoblastoma (RB1 mutation)

  • Long-term survivors of hereditary retinoblastoma have a significantly increased risk of second primary cancers comprised primarily of bone tumors, soft tissue sarcomas, and melanomas, with leiomyosarcomas and osteosarcomas accounting for more than half. So for RB1 carriers, sarcoma, melanoma, and second eye tumors are the related concerns. PubMed Central

• Neurofibromatosis Type 1 (NF1 mutation)

  • Beyond sarcoma (especially malignant peripheral nerve sheath tumors and rhabdomyosarcoma), NF1 is also associated with brain tumors (particularly gliomas), leukemia, and gastrointestinal stromal tumors (GISTs). NF1 has been associated with GISTs and malignant peripheral nerve sheath tumors (MPNSTs) in soft tissue sarcoma patients. PubMed Central

• Familial Adenomatous Polyposis (APC mutation)

  • This syndrome primarily raises colon cancer risk, but also increases risk for desmoid tumors (a type of soft tissue sarcoma), thyroid cancer, hepatoblastoma, and brain tumors.

• BRCA1/BRCA2 mutations

  • Primarily known for breast and ovarian cancer, but BRCA germline mutations have also been implicated in rhabdomyosarcoma and uterine leiomyosarcoma. Ewing sarcoma has also been associated with germline pathogenic variants in DNA damage repair genes including FANCC, CHEK2, BRCA1, and BRCA2. PubMed CentralPubMed Central

Practical takeaway

If someone is diagnosed with sarcoma, especially young, or with a family history of multiple cancers, the related cancers most worth screening for in family members depend on which syndrome is suspected:

• Sarcoma + breast cancer + brain tumor → think Li-Fraumeni (TP53)

• Sarcoma + eye cancer (retinoblastoma) + melanoma → think RB1

• Sarcoma + nerve tumors + GIST → think NF1

• Sarcoma + colon polyps → think FAP (APC)

Genetic counseling can help identify which syndrome, if any, is at play — and guide screening for the whole family.

SOURCES: [Behind drop-down]

• American Cancer Society. What Is a Soft Tissue Sarcoma? https://www.cancer.org/cancer/types/soft-tissue-sarcoma/about/what-is-soft-tissue-sarcoma.html

• American Cancer Society. What Is Bone Cancer? https://www.cancer.org/cancer/types/bone-cancer/about/what-is-bone-cancer.html

• National Cancer Institute. Soft Tissue Sarcoma Treatment (PDQ) – Patient Version. https://www.cancer.gov/types/soft-tissue-sarcoma/patient/adult-soft-tissue-treatment-pdq

• National Cancer Institute. Bone Cancer Treatment (PDQ) – Patient Version. https://www.cancer.gov/types/bone/patient/bone-treatment-pdq

• Siegel RL, Miller KD, Jemal A. Cancer Statistics, 2024. CA: A Cancer Journal for Clinicians. 2024;74(1):12–49. https://pubmed.ncbi.nlm.nih.gov/38230766/

• Sarcoma Foundation of America. About Sarcoma. https://www.curesarcoma.org/patient-resources/about-sarcoma/