(P 25) PRIMARY TREATED VERSUS REFERRED TRUNK AND EXTREMITIES SOFT TISSUE SARCOMAS: ANALYSIS OF TREATMENT IMPACT IN A SPECIALIZED CENTER IN ARGENTINA.

Objective: Soft tissue sarcomas (STS) are rare and aggressive tumors that require a complex multimodal treatment at referral centers. Yet, they are often misdiagnosed and subsequently improperly treated at local hospitals. A multidisciplinary approach is mandatory for these tumors, involving multiple specialties. Therefore, management should be carried out in reference centers for STS.
We aimed to compare oncological outcomes of trunk and extremities soft tissue STS primarily treated at a reference center vs those referred after improper treatment at non-specialized centers.

Methods: All patients with diagnosis of trunk and extremities soft tissue STS between January 2009 and May 2024 operated at our center primarily or referred to our hospital after treatment elsewhere were included. Visceral, retroperitoneal, pelvic and head/neck STS were excluded, as well as GIST and uterine sarcomas. Demographic data and tumor characteristics were evaluated (location, size, FNCLCC grade, neo/adjuvant treatment) as well as primary surgery outcomes (R classification). The cohort was divided in two groups: G1 (primary-resection group) and G2 (referred group). Overall survival (OS), local recurrence (LR), distant metastasis (DM), disease free survival (DFS), local recurrence free survival (LRFS) and distant metastasis free survival (DMFS) was compared between both groups.

Results: A total of 102 trunk and extremities soft tissue sarcomas were operated on the mentioned period, out of which 48 were primarily resected (G1) and 54 had previous resections elsewhere (G2; 34 referred for recurrent tumors and 20 referred after inadequate excision). There were no sadistically significant differences in demographic data or histopathology between groups. Data on grade was available for 91 lesions and 67% (61/91) were high-grade with no sadistically significant differences between groups. The two groups had statistically significant differences in tumor size (p < 0.001), preoperative radiotherapy (p 0.004) and R2 resection margins at first surgery (p < 0.00001) (Table 1 and Table 2). All patients in G1 had macroscopic complete bloc resections (94% R0 and 6% planned R1 margins). Residual disease was present in 35% (7/20) of the re-resection specimens. All recurrent tumors had macroscopic complete resections at our center (80% R0 and 20% R1 margins). After a median follow-up of 31 months (IQR, 13-64), we registered 19 LR (5 in G1 vs 14 in G2; p = 0.04) and 23 DM (no statically significant differences between groups). We found statistically significant differences in 5-year LRFS when comparing G1 vs. G2 (82% vs 57%, p = 0.03), and no differences in DMFS (68% vs. 73%, p=0.42), DFS (48% vs. 44%, p=0.44) and OS (81% vs. 75%, p=0.96).

Conclusion: Better local control was achieved in patients initially treated at our center. This finding may be due to tumor biology but also to an adequate primary treatment. Being surgical margin status the primary prognostic factor for LRFS, soft tissue sarcomas should be treated in referral centers where multidisciplinary approach and proper oncologic resections are standard of care. Hence the importance of a prompt referral even before any intervention in the event of suspected diagnosis.