Role of adjuvant chemotherapy in patients with localized, undifferentiated pleomorphic sarcoma of soft tissue: a population-based cohort study.

Background: Primary tumor resection is the mainstay of treatment for undifferentiated pleomorphic sarcoma (UPS); however, the necessity of adjuvant chemotherapy has been debated. We aimed to clarify the effect of adjuvant chemotherapy on survival rates in patients with UPS with localized and resectable primary lesions. Methods: This retrospective analysis included data of 2112 patients with localized UPS arising in the extremities and trunk, extracted from a registry in Japan. We estimated overall survival (OS), identified prognostic factors, and adjusted patient characteristics in the two groups treated with or without chemotherapy using propensity score matching (PSM). Results: The 5-year OS rate was 79.4%. In multivariate OS analysis, adjuvant chemotherapy was a good prognostic factor (hazard ratio 0.65; 95% confidence interval 0.48–0.9, P = 0.009). Large tumor size was the poorest prognostic factor, and OS decreased with the tumor size (P < 0.0001). In all patients, adjuvant chemotherapy prolonged OS (5-year OS: 82.3% vs. 78.6%, P = 0.03). Adjuvant chemotherapy did not affect OS in patients with tumor size < 5 cm; the benefit was strong in patients with tumor size 10 to < 15 cm (5-year OS: 79.5% vs. 66.8%, P = 0.003). Adjuvant chemotherapy efficacy was not pronounced in patients with tumor size 5 to < 10 cm (5-year OS: 87% vs. 80%, P = 0.06) and ≥ 15 cm (5-year OS: 60.7% vs. 49.5%, P = 0.08). After PSM, adjuvant chemotherapy was significantly associated with improved OS (P = 0.02). Conclusions: In patients with localized UPS, adjuvant chemotherapy tended to improve OS when tumors were ≥ 5 cm, especially when they were 10 to < 15 cm. [ABSTRACT FROM AUTHOR]