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Loss of BAP1 protein expression is an independent marker of poor prognosis in patients with low‐risk clear cell renal cell carcinoma
Author(s) -
Joseph Richard W.,
Kapur Payal,
Serie Daniel J.,
EckelPassow Jeanette E.,
Parasramka Mansi,
Ho Thai,
Cheville John C.,
Frenkel Eugene,
Rakheja Dinesh,
Brugarolas James,
Parker Alexander
Publication year - 2013
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/cncr.28521
Subject(s) - bap1 , medicine , clear cell renal cell carcinoma , renal cell carcinoma , hazard ratio , immunohistochemistry , oncology , nephrectomy , proportional hazards model , cancer , confidence interval , gastroenterology , pathology , cancer research , kidney
BACKGROUND The majority of patients diagnosed with clear cell renal cell carcinoma (ccRCC) have low‐risk disease with a < 10% chance of ccRCC‐specific death. DNA sequencing revealed that mutations in BAP1 (BRCA1 associated protein‐1) occur in 5% to 15% of ccRCC cases and are associated with poor outcomes. The vast majority of BAP1 mutations abolish protein expression. In this study, we used a highly sensitive and specific immunohistochemistry (IHC) assay to test whether BAP1 expression is an independent marker of ccRCC‐specific survival, particularly in patients with low‐risk disease. METHODS BAP1 expression was assessed, using IHC, in 1479 patients who underwent nephrectomy to treat clinically localized ccRCC. A centralized pathologist dichotomized patients as either BAP1‐positive or BAP1‐negative. The authors employed Kaplan‐Meier and Cox regression models to associate BAP1 expression with cancer‐specific survival. RESULTS A total of 10.5% of tumors were BAP1‐negative, 84.8% of tumors were BAP1‐positive, and 4.6% of tumors had ambiguous staining for BAP1. Patients with BAP1‐negative tumors have an increased risk of ccRCC‐related death (hazard ratio [HR] = 3.06; 95% confidence interval [CI] = 2.28‐4.10; P = 6.77 × 10 −14 ). BAP1 expression remained an independent marker of prognosis after adjusting for the UCLA integrated staging system (UISS) (HR = 1.67; 95% CI = 1.24‐2.25; P < .001). Finally, BAP1 was an independent prognostic marker in low‐risk patients with a Mayo Clinic stage, size, grade, and necrosis (SSIGN) score of ≤ 3 (HR = 3.24; 95% CI = 1.26‐8.33; P = .015). CONCLUSIONS This study used a large patient cohort to demonstrate that BAP1 expression is an independent marker of prognosis in patients with low‐risk (SSIGN≤ 3) ccRCC. Cancer 2014;1059–1067 . © 2014 American Cancer Society .