Background: Primary renal angiosarcoma (PRA) is an extremely rare and aggressive neoplasm. Indeed, due to its rarity, established clinical guidelines for PRA have not yet been established. In this study, we attempted to investigate its prognostic factors and treatment options. Methods: We systematically searched for articles describing PRA that had been published up until December 2021. The final cohort included 113 patients in 103 articles. The starting point of this study was the time of diagnosis and the end point was the time of recurrence and disease-specific mortality. Results: Metastasis at diagnosis was associated with poorer disease-specific survival (DSS) (p = 0.001). Tumors of more than 5 cm had poorer DSS than tumors of 5 cm or less (p < 0.001). Multivariate analysis demonstrated that primary metastatic status, and tumor size were independent prognostic factors. In cases of localized PRA, tumor sizes exceeding 5 cm had also prognostic significance for recurrence-free survival (RFS) and DSS. Surgical margins, postoperative radiation, and postoperative systemic therapy were not associated with prognoses. However, in a subgroup analysis of tumors exceeding 5 cm, postoperative radiation therapy improved RFS and DSS (p = 0.022 and p = 0.031, respectively). In cases of metastatic PRA, systemic therapy improved DSS (p < 0.001). Conclusion: We identified several prognostic factors for PRA. Among them, primary metastatic status and tumor size exceeding 5 cm were selected as independent prognostic factors. Postoperative radiation therapy for large, localized PRA and systemic therapy for recurrent and metastatic PRA might be a treatment option.
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