Soft tissue sarcomas are cancers that develop in your body’s soft tissues like muscle, fat, tendons, or cartilage. Your legs are the most common place they develop.

The American Cancer Society estimates that about 13,400 people will receive a diagnosis of soft tissue sarcoma in 2023.

Soft tissue sarcomas occur most commonly in the extremities (your arms and legs). The thigh is the most common site of occurrence, accounting for roughly 44% of all sarcomas of the extremities.

This article takes a closer look at soft tissue sarcomas in the legs, including types of sarcoma, symptoms to be aware of, and how this type of cancer is treated.

Illustration of different sized soft tissue sarcomas in the legShare on Pinterest
Stages of soft tissue sarcoma in the leg. Medical illustration by Jason Hoffman

Soft tissue sarcomas most commonly develop in the leg. Types of soft tissue sarcomas that can develop in your leg include:

  • Adult fibrosarcoma: Adult fibrosarcoma develops in the connective tissues of the arms, legs, or trunk, usually between the ages of 20 and 60.
  • Alveolar soft part sarcoma: Alveolar soft part sarcoma most commonly develops in young adults in the legs.
  • Clear cell sarcoma: Clear cell sarcoma often starts in the tendon of the arms or legs. Half of those diagnosed are over the age of 39.
  • Epithelioid sarcoma: Epithelioid sarcoma develops in the skin under the hands, forearms, lower legs, or feet. It’s most common in teenagers and young adults.
  • Fibromyxoid sarcoma: Fibromyxoid sarcoma usually starts as a painless growth in the trunk, arms, or legs.
  • Liposarcomas: Liposarcoma starts in fat tissue, usually in adults between 50 and 65 years old. They commonly develop in the thigh, behind your knee, or back of the inner abdomen.
  • Myxofibrosarcoma: Myxofibrosarcomas are most common in the arms and legs of people over 65.
  • Undifferentiated pleomorphic sarcoma: Undifferentiated pleomorphic sarcoma is most common in the arms or legs of older adults.

Learn more about types of soft tissue sarcomas.

Risk factors for soft tissue sarcomas

Risk factors for soft tissue sarcomas include:

  • receiving radiation therapy
  • having family cancer syndromes such as:
  • damage to your lymph system
  • exposure to chemicals such as:
    • vinyl chloride
    • arsenic
    • dioxin and herbicides that contain phenoxyacetic acid

The main symptoms of soft tissue sarcomas include:

  • a growing, painless lump
  • swelling
  • progressive pain or soreness as it pushes on other tissue

Sarcomas in one of your joints might cause:

  • restricted movement
  • limping
  • noticeable deforming
  • trouble walking

The main tests used to diagnose soft tissue sarcomas are imaging tests and a biopsy.

Imaging tests that might be used include:

Soft tissue sarcoma stages

The most common staging system for soft tissue sarcomas is the American Joint Committee on Cancer (AJCC)’s TNM system. This system stages soft tissue sarcomas are based on:

  • tumor size
  • number of lymph nodes it’s spread to
  • whether it’s spread to distant locations (metastasized)
  • cancer grade, a measure of the cancer’s aggressiveness from 1 to 3

The TNM system stages sarcomas of the trunk and extremities as follows:

1AThe cancer is smaller than 2 inches across and hasn’t spread to other locations. It’s grade 1, or its grade is unclear.
1BThe cancer is larger than 2 inches across. It hasn’t spread to distant locations. It’s grade 1, or its grade is unclear.
2The cancer is smaller than 2 inches across and hasn’t spread to other tissues. It’s grade 2 or 3.
3AThe cancer is between 2 and 3.9 inches across and hasn’t spread to other tissues. It’s grade 2 or 3.
3BThe cancer is larger than 3.9 inches across and hasn’t spread to other tissues. It’s grade 2 or 3.
4The cancer has spread to lymph nodes, distant areas, or both. It can be any size or grade.

Surgery is the main treatment for soft tissue sarcomas. Types of surgery include:

  • Mohs surgery (used for skin cancer lesions): With Mohs surgery, the tumor is cut into very thin layers until there are no more signs of the cancer. It allows surgeons to remove as little tissue as possible.
  • Wide local excision: The tumor and some tissue around it are removed.
  • Limb-sparing surgery: The tumor is removed, and the limb is reconstructed with grafts if necessary.
  • Amputation: Amputation involves removing an entire limb. It’s rarely required for soft tissue sarcoma.

Radiation therapy, chemotherapy, or both may be administered before or after surgery to shrink the tumor or destroy any remaining cells.

Targeted therapy and immunotherapy are sometimes used to treat soft tissue sarcomas that have spread.

Are soft tissue sarcomas of the leg curable?

Soft tissue sarcomas are curable for many people. Your cancer is most likely to be curable if your tumor is caught before it spreads to other tissues and if you have a non-aggressive subtype.

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The outlook for soft tissue sarcomas depends on which subtype you have. Sarcomas that develop in the limbs tend to have better outlooks than sarcomas that develop inside your abdomen.

The 5-year relative survival rates for soft tissue sarcomas are:

Stage5-year relative survival rate
All stages65%

Learn more about the outlook of soft tissue sarcomas.

The leg is one of the most common locations where soft tissue sarcomas develop. Sarcomas can develop in any soft tissue such as muscle, fat, or connective tissue.

Soft tissue sarcomas that develop in the leg tend to have a better outlook than cancers that develop inside your abdomen. They can often be treated with surgery to remove the tumor and surrounding tissue without the need for an amputation.