Overview

Leiomyosarcoma is a rare cancer that begins in smooth muscle tissue. Many areas of the body have smooth muscle tissue. Areas with smooth muscle tissue include the digestive system, urinary system, blood vessels and uterus.

Leiomyosarcoma most often starts in the smooth muscle tissue in the uterus, belly or leg. It starts as a growth of cells. It often grows quickly and can move to other parts of the body.

Symptoms of leiomyosarcoma depend on where the cancer starts. There may be no symptoms early in the condition.

Leiomyosarcoma is a type of soft tissue sarcoma. Soft tissue sarcoma is a broad group of cancers that begin in the connective tissues. Connective tissues connect, support and surround other body structures.

Symptoms

Leiomyosarcoma might not cause signs or symptoms at first. As the cancer grows, symptoms may include:

  • Pain.
  • Weight loss.
  • Nausea and vomiting.
  • A lump or swelling under the skin.

When to see a doctor

Make an appointment with a doctor or other healthcare professional if you have symptoms that worry you.

Causes

It's not clear what causes leiomyosarcoma. This cancer starts when something changes the cells in the smooth muscles. Many areas of the body have smooth muscle tissue. These include the digestive system, urinary system, blood vessels and uterus.

Leiomyosarcoma happens when smooth muscle cells develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy cells, the DNA tells the cells to grow and multiply at a set rate. The DNA also tells the cells to die at a set time.

In cancer cells, the DNA changes give other instructions. The changes tell the cancer cells to grow and multiply at a fast rate. Cancer cells can keep living when healthy cells would die. This causes too many cells.

The cancer cells might form a mass called a tumor. The tumor can grow to invade and destroy healthy body tissue. In time, cancer cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer.

Risk factors

Risk factors for leiomyosarcoma include:

  • Being an adult. Leiomyosarcoma can happen at any age. But it is most common in adults. It's rare in children.
  • Having certain genetic conditions. People with certain genetic conditions may have a higher risk of leiomyosarcoma. These conditions include hereditary retinoblastoma and Li-Fraumeni syndrome.

Healthcare professionals haven't found a way to prevent leiomyosarcoma.

Dec. 31, 2024

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  1. Leiomyosarcoma. National Cancer Institute. https://www.cancer.gov/pediatric-adult-rare-tumor/rare-tumors/rare-soft-tissue-tumors/leiomyosarcoma. Accessed Aug. 16, 2024.
  2. Goldblum JR, et al. Leiomyosarcoma. In: Enzinger and Weiss's Soft Tissue Tumors. 7th ed. Elsevier; 2020. https://www.clinicalkey.com. Accessed Aug. 16, 2024.
  3. Soft tissue sarcoma. National Comprehensive Cancer Network. https://www.nccn.org/professionals/physician_gls/default.aspx. Accessed Aug. 16, 2024.
  4. Devaud N, et al. Leiomyosarcoma: Current clinical management and future horizons. Surgical Oncology Clinics of North America. 2022; doi:10.1016/j.soc.2022.03.011.

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