Carmustine is primarily used for which condition?

• A. Prostate cancer
• B. Primary and metastatic brain tumors
• C. Breast cancer
• D. Leukemia

Answer: (B)

Carmustine is chosen for brain tumors because it can cross the blood–brain barrier. Its lipophilic nitrosourea structure lets it reach tumor cells within the central nervous system, where many chemotherapies cannot penetrate effectively. Once in the CNS, carmustine acts as an alkylating agent, forming cross-links in DNA and interfering with DNA replication and transcription, which leads to tumor cell death. This property makes it particularly useful for primary brain tumors like gliomas and for metastatic tumors in the brain.

For the other cancers listed, different agents are typically the mainstay of therapy, so carmustine is not considered the primary drug for those conditions.