Abstract: Based on the theory of cancer toxin pathogenesis, this paper proposes the hypothesis of cancer toxin-drug toxin coupled composite pathogenesis. It systematically elucidates the five major pathogenic characteristics of exogenous drug toxins and their pathological evolution across three stages—early, middle, and late—corresponding respectively to states of toxin-drug antagonism, dual-toxin superposition, and residual toxin latency. Guided by this coupled pathogenesis, a whole-cycle, staged diagnosis and treatment system of Wenzi Jiedu was established. This system dynamically adjusts the proportions of warming-yang, nourishing-yin, and detoxification based on the shifting balance between healthy qi and pathogenic factors and the interplay of the two toxins, while simultaneously aiming to attenuate toxicity, protect healthy qi, reverse drug resistance, clear latent toxins, and prevent recurrence and metastasis. This paper substantiates the validity of the theory through empirical data derived from the team's clinical research, as well as in vivo and in vitro pharmacological experiments. The paper inherits and systematically expands upon the cancer toxin pathogenesis theory and integrates previously fragmented research on the Wenzi Jiedu method. It establishes an integrated TCM-Western medicine pathogenesis framework suitable for the whole course of tumor progression and capable of guiding clinically stratified prescriptions, offering original TCM theoretical support for stage-specific diagnosis and treatment of malignant tumors.