Clinical Characteristics of Complex Karyotype Soft Tissue Sarcomas: A Single-Institution Cohort Study

Background and Objectives: This study aimed to describe the clinical characteristics and survival outcomes of three representative complex karyotype soft tissue sarcoma (STS) subtypes-undifferentiated sarcoma (US, primarily undifferentiated pleomorphic sarcoma (UPS)), myxofibrosarcoma (MFS), and leiomyosarcoma of soft tissue (LMS-ST)-using data from a single-institution cohort. Materials and Methods: A retrospective review of 124 patients treated at a single tertiary referral center between 2002 and 2024 was conducted. Clinicopathologic characteristics and survival outcomes were analyzed. Kaplan-Meier methods were used to estimate overall survival (OS). Cox proportional hazards regression models were applied to identify independent prognostic factors for survival, incorporating variables such as age, sex, tumor stage, and treatment modality. Results: The cohort comprised 36 cases of US, 64 of MFS, and 24 of LMS-ST. OS and survival after cohort enrollment (S-NCC) were evaluated both by subtype and across the entire cohort to assess potential differences across tumor subgroups. In both univariable and multivariable analyses, US subtypes showed poorer survival than MFS and LMS-ST. FNCLCC grade 3 emerged as a significant adverse prognostic factor for survival across all three subtypes. For FNCLCC grade 3 patients, the presence of benign prostatic hyperplasia (BPH) was significantly associated with an increased risk of death. Conclusions: Among the three subtypes, US demonstrated the most aggressive clinical course, MFS was notable for frequent local recurrence but relatively favorable survival, and LMS-ST showed intermediate outcomes. These findings highlight the clinical heterogeneity of complex karyotype STS and provide a foundation for future studies integrating molecular and multi-omics data to refine risk stratification and therapeutic strategies.