Incidence and descriptive characteristics of multifocal soft tissue sarcomas: a retrospective cohort study over two decades

Background: Soft tissue sarcomas (STS) are a rare group of adult malignancies. Multifocal type of STS is very rare. For this reason, the incidence rate, characteristic features, and oncologic outcomes of this condition are largely unknown. In this study, we report the incidence rate, characteristic features, and oncologic outcomes of multifocal STS. Methods: Medical profiles of STS patients who were treated in our university hospital between 2000 and 2022 were retrospectively reviewed. Sixteen patients with multifocal STS were identified, of whom 12 were included in the study. Pathological features, anatomical distribution, number of lesions, temporal sequence, and oncologic outcomes were extracted for the medical records. Results: Multifocal STS comprised 0.49% of all STS cases. The mean age of the patients was 54.1 yrs. Male involvement was more frequently observed (83.3%). The most frequently observed histological subtype was myxoid liposarcoma (n=5), followed by leiomyosarcoma (n=3) and low-grade fibrosarcoma (n=3). The metachronous pattern was more frequent than the synchronous pattern (8 vs. 4). The average time interval between the diagnosis of initial and secondary lesions was 12.4 mos. At a mean follow-up of 9.4 yrs, two patients (16.7%) developed local recurrence, and one patient (8.3%) developed lung metastasis. No tumor-related death was observed until the last follow-up. Conclusion: The reported incidence of multifocal STS was in line with that reported in earlier studies. However, the oncological outcomes have markedly improved. These observations could be attributed to the advancements in imaging modalities and therapeutic methods. Level of evidence: IV