From Ancient Medical Thought to Modern Health Systems: The Modern Translation of the "Fighting Poison with Poison" Principle in Cancer Therapy

"Using poison to fight poison" is an important principle in traditional Chinese medicine for treating intractable diseases. It uses the therapeutic effects of toxic medicinal agents and provides a unique strategy for modern antitumor drug development. This review examines the theoretical basis and modern development of "using poison to fight poison." Three representative toxic drugs, arsenic trioxide (ATO), cantharidin and norcantharidin, and bufalin, are discussed. Their pharmacological origins, antitumor molecular mechanisms, clinical applications, and approaches to toxicity control are systematically reviewed. Studies have shown that ATO promotes differentiation and apoptosis of acute promyelocytic leukemia cells by targeting the PML-RARα fusion protein; cantharidin and its structurally modified products mainly inhibit tumor cell proliferation and induce apoptosis through multi-target regulation; and bufalin exhibits broad anti-tumor activity by affecting multiple signaling pathways such as PI3K/Akt and MAPK. However, current research is still mainly based on basic and preclinical evidence, and there is still a lack of therapeutic window, toxicity evaluation, and high-quality clinical evidence. Future research should strengthen research on precision drug administration, toxicity monitoring, drug delivery, and randomized controlled trials to promote the transformation of traditional theories into a standardized, precise, and internationalized modern cancer treatment model.