The expression of aldehyde dehydrogenase (ALDH1), which is another putative ovarian cancer stem cell biomarker, has also been correlated with significantly lower progression free survival and the maintenance of ovarian cancer cell like properties in ovarian cancer patients [69, 70], highlighting the importance of co-targeting of ovarian cancer stem cells in combination with other therapeutics in ovarian cancer. This evidence concerns the gene ALDH1A1 and ovarian cancer.