Cyclophosphamide is widely used in the treatment of various types of cancer, including lymphoma, leukemia, and breast cancer. It works by interfering with the growth and replication of cancer cells, helping to slow or stop the progression of the disease. Additionally, it is utilized in high doses as part of conditioning regimens prior to bone marrow or stem cell transplantation to suppress the immune system and prevent rejection of the transplanted cells. Beyond oncology, cyclophosphamide is also employed in the management of severe autoimmune diseases such as lupus and rheumatoid arthritis, where it helps to modulate the immune system and reduce inflammation. Its immunosuppressive properties make it a valuable therapeutic option in these conditions, although its use is carefully monitored due to potential side effects.