Abstract 128P
Background
Leiomyosarcoma (LS) is a common soft tissue sarcoma, with an incidence between 10% - 20%. Two subgroups can be distinguished, Non-Uterine Leiomyosarcoma (NULMS) and Uterine leiomyosarcoma (ULS). ULS is a rare gynecologic tumor with a poor prognosis. This study compares the characteristics, survival, and risk of multiple primary malignancies (MPM) in both groups to optimize management and advance research.
Methods
The Surveillance, Epidemiology, and End Results (SEER) 8.4.3 program was used. We included ULS and NULS patients, according to ICD-0-3; stratified by age, race, and primary site. We excluded patients with unknown primary. We compared Overall survival (OS) and Cause Specific Survival (CSS) using Kaplan-Meier and long-rank test; and used MP-SIR to obtain the Standardized Incidence Ratio (SIR), as Observed/Expected (O/E), considered significant if P<0.05, Excess Absolute Risk (EAR) per 10,000, and 95% confidence interval (CI). Statistical analysis was conducted using IBM SPSS Statistics 27.0.1.
Results
We analyzed 13,780 patients with LS. We found 9160 patients (66%) with NULS and 4620 (33%) with ULS. NULS and ULS had a mean age of diagnosis at 62.2 and 54.5, respectively. Both groups showed a predominance of neoplasms in the white population. Distant metastases were found in 31.5% of ULS cases and 15.2% of NULS cases. NULS had a higher 5-year OS of 54.7%, while the OS for ULS was 39%. Similarly, ULS had worse 5, 3, 1 year CSS of 41.8%,53.7%, and 77%, respectively. While NULS had 5, 3, 1 year CSS of 61.5%, 69.7%, 85%, respectively. NULS had overall O/E of 1.43 (95% CI 1.34-1.52). ULS had overall O/E of 1.55 (95% CI 1.38-1.75). ULS had an increased risk of developing kidney malignancy (O/E 9.85, 95%CI 4.25-19.4) in the 0-11 months’ interval. NULS had an increased risk of developing lung and bronchus malignancy (O/E 2.48, 95%CI 1.74-3.44), melanoma (O/E 2.61, 95%CI 1.39-4.46), in the 0-11 months’ interval.
Conclusions
This study revealed disparities between ULS and NULS. ULS presented with a younger age at diagnosis and poorer prognosis. Both subtypes predominantly affected the white population. Importantly, both showed increased risks of secondary malignancies. These findings emphasize the need for vigilant monitoring and early intervention to improve patient outcomes.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.