Polybromo‐1 (PBRM1), a SWI/SNF complex subunit is a prognostic marker in clear cell renal cell carcinoma

Objective To analyse the immunohistochemical and mRNA expression of SWI/SNF (SWItch/Sucrose NonFermentable) complex subunit polybromo-1 (PBRM1) in clear cell renal cell carcinoma (ccRCC) and its impact on clinical outcomes. Patients and Methods In all, 213 consecutive patients treated surgically for renal cell carcinoma (RCC) between 1992 and 2009 were selected. A single pathologist reviewed all cases to effect a uniform reclassification and determined the most representative tumour areas for construction of a tissue microarray. In addition, mRNA expression of PBRM1 was analysed by reverse transcriptase-polymerase chain reaction. Results Of the 112-immunostained ccRCC specimens, 34 (30.4%) were PBRM1-negative, and 78 (69.6%) were PBRM1-positive. The protein expression of PBRM1 was associated with tumour stage (P < 0.001), clinical stage (P < 0.001), pN stage (P = 0.035) and tumour size (P = 0.002). PBRM1 mRNA expression was associated with clinical stage (P = 0.023), perinephric fat invasion (P = 0.008) and lymphovascular invasion (P = 0.042). PBRM1 significantly influenced tumour recurrence and tumour-related death. Disease-specific survival rates for patients whose specimens showed positive- and negative-PBRM1 expression were 89.7% and 70.6%, respectively (P = 0.017). Recurrence-free survival rates in patients with positive- and negative-expression of PBRM1 were 87.3% and 66.7%, respectively (P = 0.048). Conclusions PBRM1-negative expression is a markedly poor prognosis event in ccRCC. We encourage PBRM1 study by other groups in order to validate our findings and confirm its possible role as a useful marker in the management of patients with ccRCC.