Question

Describe the mechanism of action of radiation sensitizers with an applied example.

Hint:

Radiation sensitizers are commonly used in combination therapies to improve the effectiveness of radiotherapy in difficult-to-treat tumors.

Answer 1

Radiation sensitizers are substances that make tumor cells more sensitive to radiation therapy, enhancing the effectiveness of the treatment.
Step 1: Mechanism of Action of Radiation Sensitizers:
1. Enhancing Radiation Effect on Tumor Cells: Radiation sensitizers work by enhancing the effects of radiation on tumor cells, making them more susceptible to the damage caused by radiation. These agents may improve DNA damage repair inhibition or increase the tumor cell's ability to generate free radicals under radiation.
2. Increasing Oxygen Availability: Many radiation sensitizers work by increasing oxygen availability to the tumor cells, as oxygen enhances the formation of free radicals during radiation, leading to more extensive damage to tumor DNA.
3. Modifying Cellular Repair Mechanisms: Some sensitizers inhibit the repair of DNA damage caused by radiation, preventing tumor cells from recovering from radiation-induced injuries.
Step 2: Example of Radiation Sensitizer:
- Example - Cisplatin: Cisplatin is a chemotherapy drug that acts as a radiation sensitizer by forming platinum-DNA adducts, which inhibit DNA repair mechanisms and increase tumor cell sensitivity to radiation. It is often used in combination with radiation therapy for cancers such as head and neck and lung cancers.