(P 399) LATE LOCAL RECURRENCE (>5YEARS) OF SOFT TISSUE SARCOMA OF THE EXTREMITIES AND TRUNK WALL: PREDICTIVE FACTORS AND ONCOLOGIC OUTCOMES

Objective: The primary objective of this study was to investigate the clinicopathologic characteristics, treatment patterns, and oncologic outcomes of patients who developed LLR in a Korean tertiary referral center. Specifically, we aimed to identify features that distinguish LLR from more typical recurrence patterns, evaluate the timing and progression of metastasis following LLR, and assess the implications of LLR on survival and recurrence-free intervals. By focusing on this under-recognized subset, we hope to inform risk-adapted follow-up strategies, refine the five-year surveillance threshold, and improve long-term care for STS survivors.

Methods: A retrospective cohort study was conducted involving 279 STS patients with local recurrence, treated at a tertiary referral center in Korea. Patients were grouped into ELR ( < 5 years; n = 254) and LLR (≥5 years; n = 25). Eighteen clinical, pathological, and treatment-related variables were analyzed using chi-square tests, t-tests, and Kaplan–Meier survival analysis.

Results: Among the 279 patients with local recurrence of STS, LLR represented 9% of all local recurrences. Compared to ELR, LLR cases were more frequently associated with low- or intermediate-grade tumors (p = 0.016), infiltrative tumor borders (p = 0.014), and clear surgical margins (80% vs. 65.7%; p = 0.26). After LLR, 11 patients (44%) developed distant metastases, of whom 9 died of disease. The post-LLR 5 year survival rate was 59%.

Conclusion: This study provides one of the few detailed examinations of LLR in soft tissue sarcoma, using a Korean cohort. Our findings reveal that LLR, though relatively uncommon, comprises a distinct subgroup characterized by delayed onset, association with low- to intermediate-grade histology, clear surgical margins, and indolent histologic subtypes. Despite these features, LLR remains clinically significant due to its latent risk for distant metastasis and associated mortality.
In conclusion, late local recurrence in STS is not merely a delayed version of recurrence but may represent a distinct biological process. Future prospective studies are warranted to investigate the molecular underpinnings of LLR, assess surveillance cost-effectiveness, and explore tailored approaches to follow-up that balance patient burden with early detection benefits. Until then, clinicians should maintain a high index of suspicion for recurrence beyond five years and consider extending surveillance protocols for patients at elevated risk.