cyclophosphamide + doxorubicin + epirubicin + fluorouracil

This is a combination chemotherapy regimen consisting of four cytotoxic agents: - Cyclophosphamide, an alkylating agent that interferes with DNA replication and transcription, leading to cell death. - Doxorubicin, an anthracycline antibiotic that intercalates into DNA and inhibits topoisomerase II, preventing DNA repair and synthesis. - Epirubicin, another anthracycline closely related to doxorubicin but with a different toxicity profile; it also intercalates into DNA and inhibits topoisomerase II. - Fluorouracil (5-FU), an antimetabolite that inhibits thymidylate synthase, disrupting DNA synthesis. These drugs are used in various combinations for the treatment of breast cancer. While regimens such as FAC (fluorouracil, doxorubicin/adriamycin, cyclophosphamide) or FEC (fluorouracil, epirubicin, cyclophosphamide) are well-established in clinical practice[3][4], the simultaneous use of all four agents together is not standard but may be considered in specific clinical trial settings or investigational protocols. Each drug attacks cancer cells via distinct mechanisms at different points in the cell cycle[3][4].