Characteristics of metastasis as a prognostic factor for immunotherapy in metastatic renal cell carcinoma

Aims and background: This study aimed to evaluate the significance of characteristics of metastasis as prognostic factors in metastatic renal cell carcinoma (RCC). Patients and methods: A total of 148 patients who had received immunotherapy were included in the study. Patients were categorized in various ways according to the characteristics of metastasis, including a synchronous metastasis group (n = 77) vs a metachronous metastasis group (n = 71), and a solitary metastasis group (n = 93) vs a multiple metastases group (n = 55). Results: In the synchronous and metachronous metastasis groups, median progression-free survival was 4.3 months (95% confidence interval [CI] 2.9-5.7) and 11.1 months (95% CI 6.7-15.5), respectively (P = 0.004). Median overall survival was 17.1 months (95% CI 9.5-24.7) and 54.8 months (95% CI 38.3-71.3) in the two groups (P = 0.019). In the solitary and multiple metastasis groups, median progression-free survival was 11.0 months (95% CI 6.6-15.5) and 3.9 months (95% CI 2.6-5.2), respectively (P <0.001). Median overall survival was 55.2 months (95% CI 50.7-59.7) and 15.6 months (95% CI 10.9-20.3) in the two groups (P <0.001). Multivariate Cox proportional hazards model analysis using the clinical variables showed that T stage (P = 0.026), number of metastatic sites (P = 0.009) and time to metastasis (P = 0.019) were independent predictors of progression-free survival. Using the same variables, only the number of metastatic sites was an independent prognostic predictor of overall survival (P = 0.014). Conclusions: Our findings suggest that the time to metastasis and the number of metastases are important prognostic factors in metastatic RCC.