Why are multiple drugs often used in combination to treat leukemia and lymphoma?

• A. There are fewer toxic and side effects.
• B. The chance that one drug will be effective is increased.
• C. The drugs are more effective without causing side effects.
• D. The drugs work by different mechanisms to maximize killing of malignant cells.

Answer: (D)

Using multiple drugs in combination targets leukemia and lymphoma cells in several complementary ways. Each agent often acts on a different vulnerability—one might damage DNA, another disrupt cell division, and another inhibit a separate essential process. By attacking cancer cells through distinct mechanisms, the therapy covers more cellular weaknesses and works across different phases of the cell cycle. This makes it harder for malignant cells to survive and develop resistance, which improves overall kill rates and chances of remission. Dosing is planned to balance effectiveness with safety, so using several drugs can allow lower doses of each while still achieving a strong effect, though toxicity can still rise with combinations.