Ethnic variations in ARID1a expression in clear cell and endometrioid ovarian carcinoma.

e17073 Background: ARID1a is thought to function as a tumor suppressor; mutations in this gene have been associated with many cancers. Recent studies have found ARID1a mutations in atypical endometriosis as well as endometriosis associated ovarian carcinomas. Methods: The current study is a retrospective review of 91 cases of clear cell and endometrioid ovarian carcinomas diagnosed at Queens Medical Center in Honolulu, Hawaii between Janurary 1, 1995 to April 12, 2013. Tissue microarray was performed to evaluate loss of expression of ARID1a. Loss of expression was confirmed on whole slide sections. Clinical and ethnic information was obtained by review of medical records and the tumor registry. Ethnic information was able to be obtained for 69 of the 91 cases. Chi square or fisher’s exact tests were performed to compare loss of ARID1a expression between different racial groups. Results: Of the 91 cases studied, 20 cases exhibited loss of ARID1a expression and 71 had retained expression. There was no significant difference in expression of ARID1a among racial groups. 12 out of 48 (25%) of Asians and 1/10 (10%) of Pacific Islanders exhibited loss of expression, in comparison to 3/10 (30%) of Caucasians. There was also no significant difference when comparing Japanese and non-Japanese: 9/31 (29%), and 7/38 (18%) respectively (p value = 0.29). Conclusions: Hawaii represents a diverse ethnic population in which to study disease, with 47.5% being of Asian and Pacific Islander descent. An increased rate of clear cell ovarian carcinoma in Asians, in particular the Japanese population has been described in the literature previously. According to the current study, loss of ARID1a expression does not appear to account for this racial preference.