Ovarian cancer causes more deaths than any other cancer of the female reproductive system. The National Cancer Institute estimates that 21,990 women were diagnosed with and 15,460 women died from ovarian cancer in the U.S. last year. Likewise Cancer Research UK reports that approximately 6,600 women are diagnosed with and 4,400 women die from ovarian cancer in the UK each year. A better understanding of the molecular origins of ovarian cancer is urgently needed. A unique molecular trait of stem cells is the expression of the oct4 gene, which is silenced following early embryonic development. Accumulating evidence suggests that oct4 reactivation is a driving force in carcinogenesis. In this pilot study we examine Oct4 protein levels in tumor biopsy specimens from a random sample of patients with suspected ovarian cancer. We find that detectable Oct4 protein levels correlate strongly with the risk of death for patients with suspected ovarian cancer. The estimated hazard ratio of death for detectable Oct4 protein versus no detectable Oct4 protein was 18.9. A further Poisson regression analysis reveals that the hazard ratio increases significantly (p = 0.0093) with time since diagnosis. Our findings suggest that Oct4 protein is a prognostic variable for death from ovarian cancer, and also supports the concept that cancer stem cells are integral to the etiology of ovarian cancer.
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