The term "cancer cell reprogramming" is used to define any kind of intervention aimed at transforming cancer cells into terminally differentiated cells. Using this approach, new technologies have been applied with different methods for a more systemic approach to cancer treatment. This review reports on advances of these technologies, including our personal contributions, mainly carried out on endocrine-related cancers. Some of the interventions, aimed at reverting cancer cells into a normal phenotype, are based on the evidence that tumor development is suppressed by the embryonic microenvironment. On the basis of this rationale, experiments have been conducted using stem cell differentiation stage factors (SCDSFs) taken at different stages of development of Zebrafish embryos, oocyte extracts, or naïve human umbilical cord matrix derived stem cells (UMDSCs). SCDSFs induce significant growth inhibition on different tumor cell lines in vitro, likely because of increases in cell cycle regulatory molecules, such as p53 and pRb. Treatment with these factors activates apoptosis and differentiation related to caspase-3. This is achieved via p73 apoptotic-dependent pathway activation with a concurrent normalization of the E-cadherin and beta-catenin ratio. Extracts from prophase amphibian oocytes could reprogram relevant epigenetic alterations in MCF-7 and HCC1954 breast cancer cell lines, while un-engineered (naïve) human UMDSCs attenuated growth of MDA-231 human breast carcinoma cells. A product prepared for human treatments, containing SCDSFs at very low doses, yielded favorable results in breast cancer and in intermediate-advanced hepatocellular carcinoma. Other reprogramming interventions used in the models of breast, prostate and ovarian cancer cell lines are described. Finally, current and future perspectives of this novel technology are discussed and a new hallmark of cancer is suggested: the loss of differentiation of cancer cells.