Prognostic significance of histological invasion in high grade soft tissue sarcomas

High grade soft tissue sarcomas often show histological invasion to adjacent compartment including bone and vessel. This study aimed to evaluate histological invasion in high grade soft tissue sarcomas, clarify its impact on prognosis and devise treatment strategies. We retrospectively reviewed 133 patients with non-small round cell high grade soft tissue sarcomas surgically treated between 2001 and 2011. Clinical and histological factors examined for prognostic value included age, gender, size, depth, location, adjuvant therapy and invasion to adjacent compartment. Study endpoints included overall survival rate, event free survival rate and local recurrence free survival rate, estimated by the Kaplan-Meier method. Univariate and multivariate analyses were performed using the log-rank test and Cox proportional hazards model. Local recurrence was recognized in 14 cases (11%). The 5-year overall survival rate and 5-year event free survival rate were 82.2% and 63.6% respectively. The metastasis-free survival rate at 5 years and local recurrence-free survival rate at 5 years were 69.8% and 86.8% respectively. Histological invasion to adjacent compartment was noted in 52 cases (39%), and was significantly correlated with histological type (p = 0.01), tumor size (p = 0.009), and depth (p < 0.05). In multivariate analyses, we showed that tumor size and histological invasion were significant independent predictors of OS (hazard ratio 8.1/2.5) and EFS (hazard ratio 5.5/2.2), while only tumor size was a significant independent predictor of LRFS (hazard ratio 4.0). We evaluated the relation between histological invasion and the oncological outcomes of high grade soft tissue sarcomas. In multivariate analyses, histological invasion was found to be an independent adverse prognostic factor with hazard ratios of 2.2-2.5, suggesting that a detailed assessment of these factors is essential. Histological invasion showed a correlation with tumor size and histological type, and the surgical margin should be decided based on these factors.