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However, the expression of CDK9 in ovarian cancer from Middle Eastern ethnicity remains unknown.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>A tissue microarray of 441 epithelial ovarian cancer (EOC) samples was used to study the expression of CDK9 immunohistochemically and their clinico-pathological associations were determined. Cox proportional hazards regression model was used for univariate and multivariate analysis of recurrence-free survival.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>CDK9 over-expression was noted in 56.2\u2009% (248\/441) of EOCs and was associated with adverse clinico-pathological parameters such as distant metastasis (<jats:italic>p<\/jats:italic>\u2009&lt;\u20090.0001), stage IV tumors (<jats:italic>p<\/jats:italic>\u2009&lt;\u20090.0001), tumor recurrence (<jats:italic>p<\/jats:italic>\u2009=\u20090.0105) and high Ki-67 index (<jats:italic>p<\/jats:italic>\u2009&lt;\u20090.0001). Importantly, CDK9 over-expression was an independent predictor of poor recurrence-free survival (Hazard ratio\u2009=\u20091.51; 95\u2009% confidence interval\u2009=\u20091.15\u20131.98;<jats:italic>p<\/jats:italic>\u2009=\u20090.0030). We also found that CDK9 outperforms Ki-67 as a predictor of tumor recurrence in EOC.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Our results show that CDK9 expression correlates with markers of advanced disease in Middle Eastern EOC and is also a prognostic marker. CDK9 overexpression also identifies a subset of patients with highest likelihood of recurrence across the patient cohort. These patients may benefit from additional alternative therapies targeting CKD9.<\/jats:p><\/jats:sec>","DOI":"10.1186\/s13048-021-00827-8","type":"journal-article","created":{"date-parts":[[2021,5,20]],"date-time":"2021-05-20T07:15:42Z","timestamp":1621494942000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Cyclin-dependent kinase 9 (CDK9) predicts recurrence in Middle Eastern epithelial ovarian cancer"],"prefix":"10.1186","volume":"14","author":[{"given":"Sandeep Kumar","family":"Parvathareddy","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abdul K.","family":"Siraj","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tariq","family":"Masoodi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Padmanaban","family":"Annaiyappanaidu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ismail A.","family":"Al-Badawi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fouad","family":"Al-Dayel","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Khawla S.","family":"Al-Kuraya","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2021,5,20]]},"reference":[{"issue":"1","key":"827_CR1","doi-asserted-by":"publisher","first-page":"7","DOI":"10.3322\/caac.21590","volume":"70","author":"RL Siegel","year":"2020","unstructured":"Siegel RL, Miller KD, Jemal A. 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Research Advisory Council (RAC) granted waiver of informed consent for use of retrospective patient case data under project RAC# 2140 033. All the methods were carried out in accordance with relevant guidelines and regulations.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethics approval and consent to participate"}},{"value":"Not applicable.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Consent for publication"}},{"value":"The authors declare that they have no competing interests.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"69"}}