Melphalan is primarily used in the treatment of multiple myeloma, a type of blood cancer that affects plasma cells in the bone marrow. It is also employed in the management of ovarian cancer, particularly in cases where the disease has spread beyond the ovaries. Additionally, melphalan is utilized as a conditioning treatment prior to hematopoietic stem cell transplantation, helping to destroy bone marrow cells and make room for new, healthy stem cells. In some instances, it is used to treat certain types of melanoma and other cancers when other treatments have not been effective. Melphalan works by interfering with the DNA replication process in cancer cells, ultimately leading to their destruction. Due to its potent effects, it is often administered under close medical supervision to monitor and manage potential side effects.