Lomustine is primarily used in the treatment of certain types of brain tumors, including glioblastoma multiforme and medulloblastoma. It is also effective against Hodgkin's lymphoma and other forms of cancer, particularly when other treatments have not been successful. As an alkylating agent, it works by interfering with the DNA of cancer cells, preventing their replication and growth. Lomustine is often administered orally, making it convenient for patients who require long-term treatment. It is sometimes used in combination with other chemotherapy drugs or radiation therapy to enhance its effectiveness. Due to its potential side effects, such as bone marrow suppression, patients undergoing treatment with lomustine require regular monitoring of blood counts and other health parameters.