(P 058) SARCOPENIA AS A NEGATIVE PROGNOSTIC FACTOR IN LOCALIZED EXTREMITIES/TRUNK WALL SOFT TISSUE SARCOMAS

Objective: Sarcopenia is the pathological reduction of skeletal muscle mass that has recently been pointed out as a negative prognostic factor in several tumors. Our purpose was to evaluate sarcopenia impact on survival outcomes of patients (pts) affected by extremities and trunk wall soft tissue sarcomas (ESTS).

Methods: We included pts affected by localized, primary ESTS diagnosed between 2011 and 2020, who underwent basal and contrast-enhanced CT scan before any treatment and for whom high-quality images were available. Pts were treated at referral sarcoma centers of our region and discussed within their multidisciplinary tumor board. We selected a basal single CT slice at the level of the third lumbar vertebra. Using a commercial software (SliceOMatic), we traced a region of interest delineating the cross-sectional skeletal muscle area (SMA) along with the muscle density (MD) computed in Hounsfield units (HU). On the same slice, we also calculated the subcutaneous fat area (SFA) and the visceral fat area (VFA). SMA was subsequently normalized by the square of the patient’s height computing the skeletal mass index (SMI) in cm2/m2. According to available literature, cut-offs for normal SMI were set at 52 and 39 cm2/m2 for men and women, respectively. Pts with SMI values below these cut-offs were defined sarcopenic. For MD, SFA and VFA we compared patients above and below median values. We explored the correlation of the different parameters with post-surgical complications and survival outcomes (overall survival, OS, and post-relapse survival, PR-OS) estimated by Kaplan-Meier method. Hazard ratios (HR) were estimated by Cox regression. To evaluate baseline prognostic characteristics, we computed for each pt the predicted 5- and 10-year OS according to Sarculator. Statistical analyses were performed with SPSS v28.0 and tests were 2-sided whenever indicated.

Results: 157 pts, median age 62 (IQR 46-72), male/female 85/72, were included. Histotypes: 34 (21.7%) UPS, 29 (18.5%) myxoid liposarcoma, 25 (15.9%) leiomyosarcoma, 12 (7.6%) myxofibrosarcoma, 11 (7.0%) MDM2-amplified liposarcoma, 7 (4.5%) MPNST, 5 (3.2%) synovial sarcoma, 34 (21.7%) other ESTS. Median SMAs, SMIs, and MD were 155.5 cm2 (133.7-173.1), 52.1 cm2/m2 (44.1-57.1), and 31.7 HU (24.3-40.1) for men; 103.9 cm2 (91.0-117.1), 39.1 cm2/m2 (35.2-42.8), and 35.3 HU (21.4-41.9) for women. Sarcopenia rate was not significantly different in patients ≥65 years (56.9% vs 43.8%, p=0.156), nor according to baseline Sarculator predicted outcomes.
129 pts were included in survival analysis. Median follow up was 54 months. OS was significantly worse for sarcopenic pts with a median of 58.4 months (95%CI 3.9-113.0) vs not reached (NR) with a doubled risk of death (HR 2.195, 95%CI 1.265-3.809, p=0.005). A similar effect was observed for low MD with a median OS of 58 months (14.1-30.7) vs NR (HR 1.838, 1.066-3.171). No difference was observed for SFA and VFA.
Consistently with other data, sarcopenic pts showed increased post-surgical complications particularly in pts who did not receive preoperative treatments (any complication 39.4% vs 16.7%, p=0.042).
In the 47 pts who had a relapse event, PR-OS was worse, though borderline statistically significant, for sarcopenic pts: median OS 14.6 months (0-34.8) vs 39.6 (30.2-48.9), HR 1.893 (0.925-3.875), p=0.081.
Finally, to explore whether the addition of sarcopenia might further improve patients’ stratification by means of Sarculator, we developed a score based on predicted 10-year OS (1 point if ≥60%) and SMI (1 point if high). This 3-points score well stratified our patient population: median OS 16 months (3.0-29.2) vs 102 (19.9-184.9) vs NR (NR-NR) for score 0, 1, and 2, respectively (p< 0.001). Estimated 5- and 10-year OS were 33.3% and 26.7%, 59.1% and 44.3%, 77.6% and 66.5% for score 0, 1, and 2, respectively.

Conclusion: With the limitations of a retrospective analysis, our study suggests to further explore sarcopenia as a negative prognostic factor in ESTS pts. Furthermore, sarcopenic pts had a higher incidence of post-surgical complications and those with a baseline predicted 10-year OS < 60% showed a particularly worse prognosis.