(P 102) INTERLEUKIN-6 IN RELATION TO TUMOR BEHAVIOR AND EARLY RECURRENCE IN PRIMARY LOCALIZED SOFT TISSUE SARCOMA

Objective: The diversity of clinical and pathological characteristics of soft tissue sarcoma (STS) presents a challenge for the prediction of prognosis. Recently, pretreatment inflammatory markers have gained interest as predictive factors for tumor aggressiveness and survival in cancer patients. The aim of this study is to evaluate interleukin-6 (IL-6) as a predictive biomarker for aggressive behavior and early recurrences in STS.

Methods: 118 patients with primary, localized soft tissue sarcoma were retrospectively reviewed. IL-6 serum levels were obtained prior to treatment for all patients. Early recurrence was defined as a disease relapse (local or distant) within the first year after diagnosis. The association of pretreatment elevated IL-6 was studied in relation to clinicopathological variables including tumor grade, tumor depth, tumor location, tumor size, presence of tumor necrosis on imaging, pathologic necrosis and mitotic count by using Chi-square tests. Survival data was analyzed using Log-rank tests and Cox regression to identify prognostic factors for early recurrence.

Results: Pretreatment IL-6 elevation was associated with higher tumor grade, increased size, necrosis on imaging, pathologic necrosis and a higher mitotic count. Tumor depth and location were not associated with IL-6 level. Early recurrences were found in 23 of 118 patients (19.5%): 7 local, 15 distant recurrences and 1 with both manifestations. Univariate analysis revealed that tumor grade (low vs high, p = 0.008), tumor depth (superficial vs deep, p = 0.005), pathologic necrosis (absent vs present, p = 0.002) and IL-6 serum level ( < 7 vs ≥ 7 ng/L, p = 0.012) were significantly associated with early recurrence. IL-6 level did not retain its prognostic value in multivariate analysis as independent predictor for early recurrence, although the number of cases were small.

Conclusion: Increased IL-6 serum level in STS is associated with an aggressive phenotype. STS that recur early are more often of higher grade and deep-seated, but are also associated with increased plasma levels of IL-6.