Atrimustine is an antineoplastic agent primarily used in oncology for the treatment of certain cancers, including advanced prostate cancer and breast cancer. It functions as an alkylating agent that binds to DNA, inhibiting cancer cell replication and leading to cell death. This mechanism targets rapidly proliferating cells characteristic of tumors. Atrimustine is often employed when other therapies fail or in cases of disease progression, and it may be used in combination with other chemotherapeutic agents to enhance efficacy. Its administration requires close medical supervision due to potential severe side effects.