Abstract
Relevance: One of the key challenges in modern oncology remains tumor resistance to therapy and the high risk of relapse, which are largely associated with cancer stem cells (CSCs). Regulatory T cells (Tregs) are considered one of the factors supporting the stem-like phenotype of tumor cells; however, the mechanisms of their interaction remain insufficiently studied. Despite the growing number of studies addressing the impact of Tregs on CSCs in breast cancer (BC), colorectal cancer (CRC), and glioblastoma (GBM), the fragmented and contradictory findings necessitated the con-duct of this analytical review. The study aimed to systematize experimental, review, and clinical data on Treg-CSC interactions and to formulate hypotheses that define future research directions and therapeutic approaches. Methods: This comprehensive literature search was conducted in Medline (PubMed), NCBI, and Google Scholar databases covering the years 2015 to 2025. The following terms were used: “T-regulatory cells” and/or “cancer stem cells” and/or “breast cancer stem cells” and/or “colorectal cancer stem cells” and/or “glioma stem cells.” Results: The literature review showed that Tregs, both directly and indirectly, activate key signaling cascades (TGF-β/SMAD, NF-κB/CCL1, IL-10/STAT3) that maintain the stem-like phenotype of tu-mor cells and are associated with poor prognosis in BC, CRC, and GBM. Conclusion: Tregs and the molecular mechanisms they mediate can be considered potential targets for anticancer therapy; however, their use in clinical practice requires further experimental and clinical research.