Since an ongoing interaction between a potential cancer cell and its microenvironment is a necessary requirement for their co-evolution towards a malignant disease state, a future success of cancer prevention will depend on how effectively a vaccination strategy simultaneously acts on emerging pretumor cells as well as on its microenvironment. Based on the assumption and theory that a placental vaccine could induce humoral and cell-mediated immune response against both the embryo-like antigens and angiogenic factors that are common to placental and cancer cells, this vaccination would create an immunological state in normal healthy individuals which would result in rejection of foreign nascent transforming cells, or cancer initiating cells (so called cancer stem cells). Immunoplacental Vaccine (Human placenta whole cell lysates) prepared upon Filatov's method, consisting of heat shock proteins and associated placental peptide complexes-version of homologous non-mutated proteins that are found on different kinds of epithelial cancer cells, when intradermal coinjected with an adjuvant, i.e. BCG-Vaccine, in normal healthy individuals, may function as a multi-epitope vaccine; the body recognizes the placental antigens of this vaccine as foreign, and thus stimulates a cross-reactive humoral and cell-mediated immune response targeting cancer tumor-associated antigens (TAA), as well as proteins that aid in cancer development. Also, by eliciting of critical cytokines at the vaccination site may result in cytokine-network balancing and in promoting Th1 cell-mediated immunity in the local microenvironment of preneoplastic to neoplastic transformation. Thus, this vaccination approach, by fine-tuning T-cell repertoire, T-cell regulation and cytokine-network balancing in the local microenvironment of preneoplastic to neoplastic transformation, acts on both "abnormal cells" and their "abnormal microenvironment", in which abnormal clones develop.