introduction: Breast cancer (BC) is a leading global malignancy in women. Although central to treatment, chemotherapy may paradoxically promote metastasis. The role of metabolic changes in chemotherapy- induced metastasis remains unclear. This study aims to investigate the association between metabolic alterations and BC metastasis after CMF (cyclophosphamide (CCP), methotrexate (MTX), and 5-fluorouracil (5-FU)) chemotherapy. Methods: A murine BC model treated with CMF was used. Metabolomic profiling identified altered pathways. Metastasis was assessed via tumor growth, hematoxylin and eosin (H&E), and immunohistochemistry (IHC). Phospholipid metabolism was inhibited with idelalisib combined with CMF. Traditional Chinese medicine (TCM) components were screened. Epicatechin (EC) was identified as a modulator of phospholipid metabolism and tested in CMF. Results: Metabolomic analysis revealed a marked upregulation of phospholipid metabolism in CMF-treated BC mice, which was linked to enhanced metastasis. Intervening with idelalisib in combination with CMF abolished these protumorigenic effects. Among the screened TCM components, EC was identified as a modulator of phospholipid metabolism. Similarly, the combination of EC and CMF maintained chemotherapy's antitumor efficacy while substantially reducing metastatic spread. Discussion: Our findings reveal that CMF chemotherapy induces phospholipid metabolic reprogramming, which drives BC metastasis. Targeting this pathway—either through pharmacological inhibitors (idelalisib) or natural compounds (EC)—can mitigate chemotherapy-induced metastasis without compromising tumor suppression. This suggests that metabolic modulation could be a viable strategy to enhance chemotherapy efficacy. Conclusion: Upregulated phospholipid metabolism is a critical mechanism behind chemotherapy-induced BC metastasis. Combining CMF with phospholipid-targeting agents (idelalisib or EC) offers a promising therapeutic approach to optimize chemotherapy outcomes. These results provide a theoretical foundation for developing novel combination therapies in BC treatment.
Yu et al. (Thu,) studied this question.