Sarcomatoid component and the risk of renal cell carcinoma: a systematic review and meta-analysis

The sarcomatoid component is increasingly reported to be associated with the prognosis of patients with renal cell carcinoma (RCC), but the results remain controversial. We conducted a meta-analysis to quantitatively evaluate the impact of the sarcomatoid component on prognosis of patients with RCC. Systematic detailed searches were performed on PubMed, EBSCO, EMBASE, and the Cochrane Library until to October 31, 2016. Based on a fix-effects model or random-effects model, the pooled hazard ratio (HR) with 95% confidence interval (CI) for overall survival (OS), progression-free survival (PFS), or cancer-specific survival (CSS) were used to evaluate the potential risk. Twenty-three studies met the inclusion criteria for the present study and contained a combined total of 27856 study subjects. The presence of the sarcomatoid component was associated with poor OS (HR = 1.89; 95% CI, 1.50-2.38, p < 0.00001), PFS (HR = 2.04; 95% CI, 1.45-2.87, p < 0.0001) and CSS (HR = 1.87; 95% CI: 1.48-2.37, P < 0.00001) in RCC patients. Additionally, while the presence of the sarcomatoid component was more common in patients with a higher tumor stage (T3-4) and Fuhrman grade (G3-4), there was no correlation between presence of the sarcomatoid component and gender or metastasis status. The results of this meta-analysis suggest that the presence of sarcomatoid component is associated with an increased risk and poorer survival in RCC patients. The sarcomatoid component plays an important role in the carcinogenesis and prognosis of RCC.