What is the primary purpose of colony-stimulating factors in cancer therapy?

• A. Kill cancer cells directly
• B. Increase neutrophil count to reduce infection risk during chemotherapy
• C. Increase platelet production
• D. Suppress bone marrow function

Answer: (B)

Colony-stimulating factors are used to counter chemotherapy-induced neutropenia by stimulating the bone marrow to produce neutrophils. The main goal is to raise neutrophil counts to reduce the risk of infections during chemotherapy, since neutropenia leaves patients highly vulnerable to bacterial and fungal infections. By boosting neutrophil production (for example, with G-CSF), these agents shorten the duration of neutropenia and help patients stay on planned chemotherapy schedules, which can improve overall treatment effectiveness. They do not directly kill cancer cells, they are not primarily used to increase platelet production, and they do not suppress bone marrow—in fact they support its recovery. Common examples include agents like filgrastim and pegfilgrastim that specifically enhance neutrophil recovery. Side effects can include bone pain and injection-site reactions.