How does radiation therapy function to treat cancer?

Radiation therapy functions primarily by damaging the DNA of cancer cells. Cancer cells, like all cells, rely on intact DNA to replicate and grow. When high doses of radiation are directed towards a tumor, the energy from the radiation creates breaks in the DNA strands within the cancer cells. These breaks can prevent the cells from dividing and multiplying effectively, thereby inhibiting tumor growth.

In addition to direct DNA damage, the broken DNA can trigger cellular death mechanisms, leading to the demise of the cancerous cells over time. This targeted approach allows for the destruction of malignant cells while minimizing damage to surrounding healthy tissue, although some collateral damage can occur. Understanding the mechanism of action of radiation therapy elucidates the rationale for its use in various types of cancer treatment, particularly for localized tumors.

The other options do not accurately represent the primary mechanism of radiation therapy. Encouraging cancer cell growth or improving blood flow to tumors does not contribute to their destruction and may instead lead to tumor progression. Enhancing the immune response, while beneficial in some therapeutic contexts, is not the primary action of radiation therapy in directly targeting and damaging cancer cells.