(P 504) WHY DO SOME PATIENTS WITH SYNOVIAL SARCOMA HAVE BETTER FUNCTIONAL OUTCOMES AFTER RESECTION SURGERY? ANALYSIS OF 102 CASES

Objective: Synovial sarcoma (SS) is a very aggressive mesenchymal tumor with partial epitelial differentiation and a high potential for metastasis. The presence of t(X;18)(p11.2;q11.2) is a pathognomonic feature of synovial sarcoma. SS is considered the fourth most common sarcoma at any age. It’s prognosis is very por with an expected 5-year survival between 50-60% in adults. Survivors must face with major functional sequelae secondary to large muscle resections and adjuvant treatments such as radiotherapy. Functional outcomes are important for oncologic patients undergoing limb sarcoma surgery.
The aim of this study is to identify predictors of postoperative function in musculoskeletal oncology patients that came through a synovial sarcoma resection surgery.

Methods: We retrospectively reviewed 102 consecutive cases of synovial sarcoma treated in our institution between 1983 - 2016.
We went over multiple variables related to the most commonly used functional outcome scales (MSTS-ISOLS score) in order to analyze possible risk factors for poor functional outcomes.
For hypothesis testing, after confirming the normality of the distributions in the numerical variables using the Kolmogorov-Smirnoff test, we used ANOVA and the parametric Student T-test. For qualitative variables, we used Pearson’s Chi-square test or Fisher’s exact test.

Results: 102 cases were included in our study. 60 men (58.8%) and 42 women (41.2%). The mean age at diagnosis was 37.9 years ±17.5 (10-80). In our sample the third decade of life was the one with the highest incidence of synovial sarcoma cases followed by the fifth decade of life. Regarding to the functional outcomes, no statistically significant differences were observed with respecto to gender, location, histological variant or degree of differentiation, the time elapsed between symptom onset and first consultation, diagnosis or initiation of treatment.
Statistically significant differences were observed according to the mean age of the patients with improvement in the youngest (p=0.036), specially in patients under 25 years. Statistically significant differences were also observed for the functional scale results (p < 0.001) according to the AJCC staging. With regard to size, both the largest tumor diameter (measured in centimeters) (p=0.014) and tumor volume (measured in cubic centimeters) (p=0.03) were statistically significant regarding functional outcomes. Statistically significant differences were observed in cases with no local recurrence (p < 0.001) and in those with no distant metastases (p < 0.001). Comparatively and also statistically significantly (p < 0.001), the surgical technique implies the functional results, worse functional results are to be expected in amputations compared to limb salvage. Statistically significant differences were observed with respect to treatment (TABLES 226-227) with chemotherapy (p < 0.001) and with respect to combined treatment by surgery, radiotherapy (RDT) and chemotherapy (QT) (p < 0.001) in favor of the association to chemotherapy treatment. However, no significant differences were obtained with respect to functional outcomes and the association of radiotherapy with surgical treatment.

Conclusion: Younger patients, patients undergoing limb salvage compared to amputation, patients with smaller tumor, those treated with chemotherapy or combined treatment, and patients without recurrences or dissemination, presented better functional results after undergoing synovial sarcoma surgery.