In cancer treatment, what do radiation and chemotherapy primarily disrupt?

The correct answer is that radiation and chemotherapy primarily disrupt cell division. Both of these treatments target rapidly dividing cells, which is a hallmark of cancerous growth. During cell division, DNA must be replicated and the cell must go through specific phases, including mitosis. Radiation damages the DNA directly, leading to mutations and cellular apoptosis if the damage is severe enough. Chemotherapy uses drugs that interfere with various aspects of the cell cycle, inhibiting the synthesis of DNA or disrupting microtubule function, which are critical for mitosis.

Since cancer cells typically divide much more frequently than normal cells, these treatments aim to target and kill those rapidly proliferating cells, ultimately slowing or stopping tumor growth. This is why someone undergoing cancer treatment often experiences side effects like hair loss and a weakened immune system, as other fast-dividing normal cells are also affected.