Tumor initiation and progression are driven by a subpopulation of tumor cells that possess stem cell properties and are resistant to traditional cancer treatments—the cancer stem cells (CSCs).CSCs have been identified in most types of cancer, including ovarian, bladder tumors and gliomas, and can be separated from the rest of the tumor cells using appropriate markers.CSC markers and signature genes have proven to be predictive of cancer progression and clinical outcome.More aggressive or refractory cancers contain more CSCs, underscoring the clinical importance of this tumor cell population.Anticancer therapies should include as a key element an assessment of the abundance and persistence of CSCs.In this study 51 cases of high-grade gliomas were analyzed (CD133, CD 15, Sox-2 and Nanog).Overall expression of CD133 showed correlation with the survival of the patients.CD133 has some prognostic potential in gliomas patients.CD 133 and Ki67 expression was demonstrated prognostic factor of disease progression and clinical outcome.Since CD133 was found on the surface of tumor cells in invasive front, this relation may have a potential as clinical marker in patients suffering lower grade gliomas.Ovarian stem cells were studied in 73 primary tumors, 15 with metastasis.CD44 is expressed in 40% to 60% of the primary ovarian tumors and may be specific to certain histologies.In serous ovarian cancer it was positive in 42.8%of primary tumors, but in 85.7% of metastasis.Bladder cancer cell populations do appear to include CSCs, although their abundance remains unknown.Oct 3/4 was found expressed in 0, Sox-2 in 25% of bladder cancers (75 cases).