Histology is a Prognostic Indicator After Pulmonary Metastasectomy from Renal Cell Carcinoma

There are only a few detailed reports concerning the prognosticators following surgical resection of pulmonary metastases (PMs) from renal cell carcinoma (RCC). We investigated the prognosis of patients with RCC PMs undergoing pulmonary metastasectomy and identified prognostic factors in a multi-institutional retrospective study. We retrospectively evaluated 84 patients who underwent resection of PMs from RCC between 1993 and 2014. We assessed the clinicopathological characteristics, focusing on the histological findings of PMs. We classified the histology into three types: pure clear cell carcinoma (N = 68), clear cell carcinoma combined with other histology type (N = 8), and non-clear cell carcinoma (N = 8). We examined the relationship between these histological types and the prognosis of patients with PMs from RCC. Complete resection was achieved in 78 patients (93%). The 5-year overall survival rate after metastasectomy was 59.7%. In multivariate analysis, three factors were found to be independent favorable prognostic factors of overall survival after lung metastasectomy [tumor size < 2 cm, hazard ratio (HR) = 0.31, 95% confidence interval (CI) 0.13-0.78, P = 0.012; clear cell type, HR = 0.37, 95% CI 0.16-0.83, P = 0.025; and complete resection, HR = 0.27, 95% CI 0.10-0.78, P = 0.015]. This study indicates that a histological finding of the clear cell type is a significant favorable prognostic factor in addition to complete resection and a tumor size < 2 cm. Histological evaluation of PM lesions is important for predicting survival after metastasectomy.