Leiomyosarcoma (LMS)

What is leiomyosarcoma?

Leiomyosarcoma (LMS) is a smooth muscle tumor that can occur in almost any part of the body.1,2 Despite being a common type of soft tissue sarcoma (STS), LMS is a rare type of cancer that is resistant, unpredictable, and often recurs later in life.1

LMS accounts for 10%–20% of all new STSs.2 LMS originates in either smooth muscle cells or the precursor mesenchymal stem cells that differentiate into smooth muscle cells.3 For this reason, LMS shows a predilection for soft tissues and the adominopelvic organs and can arise in the abdomen, retroperitoneum, larger blood vessels and the uterus.1,2

LMS is less likely to be found in the extremities, where it accounts for 10–15% of limb sarcomas.2 Uterine LMS is the most common type of uterine sarcoma and is the largest site-specific group of LMS.2

What causes leiomyosarcoma?

The cause of LMS is not clearly defined; however, genomic profiles of LMS tumors often show loss of chromosomes that are involved in cell proliferation pathways or tumor suppressor genes.4 

Research shows that the most frequently mutated genes are TP53, RB1, and ATRX. Mutations in other genes involved in apoptosis, cell-cycle regulation, angiogenesis and growth factor signaling have been proposed to potentially have a role in LMS carcinogenesis.4

In the majority of cases, LMS is driven by a perturbed tumor suppressor network, giving rise to whole-genome duplication and large-scale genomic instability. This accelerates tumor evolution.5 

The signs and symptoms of leiomyosarcoma

LMS typically presents with non-specific symptoms that result from the displacement of structures in specific anatomic locations of the primary tumor and metastases, rather than invasion.2 

Generally, if the tumor is present only at the cutaneous level, then it may appear as small nodules, but a deep tumor may arise near medium to large veins.6 In some cases, LMS can be found near large, vascularized structures where there is a risk that the tumor may obstruct the vessel, leading to decreased blood flow.6 

As LMS is commonly found in the abdominopelvic organs, patients with uterine LMS may present with abnormal uterine bleeding or abnormal uterine growth.3,4 

The estimated incidence of leiomyosarcoma

LMS has an incidence rate of 1.2 cases per 100,000 person-years.7 The annual incidence of LMS is less than 2 women per 100,000.8 Approximately 4,000 patients are diagnosed with LMS annually in the United States.9 

As in STSs in general, the overall incidence of LMS increases with age and peaks in people’s 70s.2 Uterine LMS, however, appears earlier, presenting from the 30s into old age, being most prevalent in perimenopausal women – typically in their 50s.2 The incidence according to sex depends on tumor location, with a greater predominance of women among patients with retroperitoneal and inferior vena cava LMS.2 In contrast, men show a mild prevalence among patients with noncutaneous soft tissue sites and cutaneous LMS.2 

Determining a diagnosis of leiomyosarcoma

At present, no specific laboratory or radiographic tests are clinically available to assist with LMS diagnosis.3 

The gold standard for LMS diagnosis is morphologic diagnosis based on microscopic examination.3 Microscopic examination is supported by immunohistochemistry, classical cytogenetics, and molecular testing.3 Diagnosing LMS can be complicated by overlapping features of other benign or malignant neoplasms.10 

One such overlapping condition is leiomyoma, which is a common benign tumor of the uterus.11 Computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound can prove useful in distinguishing between LMS and leiomyoma.11 As a suspected leiomyoma is often managed conservatively or with minimally invasive treatments, the misdiagnosis of LMS for a benign leiomyoma could potentially result in significant treatment delays and increase morbidity and mortality.11

Imaging tests, including CT or MRI, are needed to stage the disease.3 CTs are used for retroperitaneal and visceral lesions while MRI is preferred for head, neck or limb tumors.3

What is the prognosis of leiomyosarcoma?

Histologic grade, tumor size, and tumor depth are the three most important prognostic factors in patients diagnosed with LMS.3 Tumor depth is a strong prognostic factor for disease recurrence and mortality, with deep tumors associated with worse outcomes.12  

Evidence suggests that high-grade malignant soft tissue tumors have a low rate of survival for patients with LMS.13 Moreover, the Musculoskeletal Tumor Society (MSTS) stage, the presence of metastases, and the size of the primary lesion are closely and statistically related to patient death at a mean of 3 years after discovery.13 However, in patients with MSTS stages 1 or 2 (non-metastatic), the survival rate is improved.13 In addition, the survival rate is dependent on the tumor site; the 5-year survival rate may be 50% for upper limbs, 23% for lower limbs and 29% for the trunk wall.14 

CT, computed tomography; LMS, leiomyosarcoma; MRI, magnetic resonance imaging; MSTS, Musculoskeletal Tumor Society; STS, soft tissue sarcoma.


  1. Singh Z. J Cancer Res Pract 2018;5(1):1–8. 
  2. George S, Serrano C, Hensley ML, et al. J Clin Oncol 2018;10;36(2):144–150.
  3. Mangla A, Yadav U. Leiomyosarcoma. In: Leiomyosarcoma. Treasure Island Florida: StatPearls Publishing; 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551667/. Last accessed September 2023.
  4. Cui RR, Wright JD, Hou JY. BJOG 2017;124(7):1028–1037.
  5. Chudasama P, Mughal SS, Sanders MA, et al. Nat Commun 2018;9:144.
  6. Mangla A, Yadav U. Leiomyosarcoma. In: Leiomyosarcoma. Treasure Island Florida: StatPearls Publishing; 2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551667/. Last accessed September 2023.
  7. Toro JR, Travis LB, Wu HJ, et al. Int J Cancer 2006 15;119(12):2922–2930. 
  8. Brooks SE, Zhan M, Cote T, et al. Gynecol Oncol 2004;93:204–208.
  9. Ries LAG, Young JL, Keel GE, Eisner MP, Lin YD, Horner M-J (editors). SEER Survival Monograph: Cancer Survival Among Adults: U.S. SEER Program, 1988–2001, Patient and Tumor Characteristics. National Cancer Institute, SEER Program, NIH Pub. No. 07-6215, Bethesda, MD, 2007. 
  10. Grossmann AH, Layfield LJ, Randall RL. Sarcoma 2012;2012:380896.  
  11. Sun S, Bonaffini PA, Nougaret S, et al. Diagn Interv Imaging 2019;100(10):619–634. 
  12. Francescutti V, Sanghera SS, Cheney RT, et al. Sarcoma 2015;2015:325049.
  13. Mankin HJ, Casas-Ganem J, Kim JI, et al. Clin Orthop Relat Res 2004;421:225–231.
  14. Mestiri S, Elghali MA, Bourigua R, et al. Rare Tumors 2019;11:2036361318820171.
MED-ALL-LMS-2100001 | September 2023
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