Loss of ARID1A expression is associated with poor prognosis in patients with stage I/II clear cell carcinoma of the ovary

Recent studies have shown that somatic mutations in the AT-rich interactive domain 1A (SWI-like) gene (ARID1A) are the most common genetic changes in clear cell carcinoma of the ovary (CCC). A gene mutation of ARID1A was found in approximately half of CCC cases, and led to absence of the encoded protein and inactivation of the putative tumor suppressor. Here, we investigated whether ARID1A could be a prognostic biomarker for this disease. We analyzed the protein expression of ARID1A in CCC from 112 patients by immunohistochemical staining, and evaluated the association of these molecular parameters with clinical outcome. The loss of ARID1A expression was found in 39 % (44/112) of CCC, and was not associated with patient age, FIGO stage, and status of residual tumor. The 5-year survival rate for FIGO stage I or II patients with negative tumor expression of ARID1A was lower than those with positive tumor expression of ARID1A (74 % vs 91 %), but this difference was not observed in FIGO stage III or IV patients. Multivariable analysis revealed that ARID1A expression was an independent prognostic factor in FIGO stage I or II CCC patients. ARID1A may be a biomarker that is predictive of the outcome of FIGO stage I and II CCC.