Metastatic Pattern of Truncal and Extremity Leiomyosarcoma: Retrospective Analysis of Predictors, Outcomes, and Detection

Leiomyosarcomas (LMS) are a heterogenous group of malignant mesenchymal neoplasms with smooth muscle origin and are classified as either non-uterine (NULMS) or uterine (ULMS). Metastatic pattern, prognostic factors, and ideal staging/surveillance studies for truncal and extremity LMS have not been defined. A retrospective analysis of patients diagnosed with histopathology-confirmed truncal or extremity LMS between 2009 and 2019 was conducted. Data collected included demographics, tumor characteristics, staging, surveillance, and survival endpoints. The primary site was defined as: (1) extremity, (2) flank/Pelvis, or (3) chest wall/Spine. We identified 73 patients, 23.3% of which had metastatic LMS at primary diagnosis, while 68.5% developed metastatic disease at any point. The mean metastatic-free survival from primary diagnosis of localized LMS was 3.0 +/- 2.8 years. Analysis of prognostic factors revealed that greater age (>= 50 years) at initial diagnosis (OR = 3.74, p = 0.0003), higher tumor differentiation scores (OR = 12.09, p = 0.002), and higher tumor necrosis scores (OR = 3.65, p = 0.026) were significantly associated with metastases. Older patients (>50 years, OR = 4.76, p = 0.017), patients with larger tumors (>= 5 cm or >= 10 cm, OR = 2.12, p = 0.02, OR = 1.92, p = 0.029, respectively), higher differentiation scores (OR = 15.92, p = 0.013), and higher necrosis scores (OR = 4.68, p = 0.044) show worse survival outcomes. Analysis of imaging modality during initial staging and during surveillance showed greater tumor detection frequency when PET imaging was employed, compared to CT imaging (p < 0.0001). In conclusion, truncal and peripheral extremity LMS is an aggressive tumor with high metastatic potential and mortality. While there is a significant risk of metastases to lungs, extra-pulmonary tumors are relatively frequent, and broad surveillance may be warranted.