Medical Science Question: Radiation and Cancer
Question:
Exposure to ionizing radiation can cause cancer, yet a beam of ionizing radiation can also be used to cure certain types of cancer. Why is this?
- Only alpha particles cause cancer, so the other types of ionizing radiation can be used to cure it.
- If the energy of the ionizing radiation is high enough, it will kill cancer cells.
- If you already have cancer, ionizing radiation will not hurt you.
- If a person is treated for one type of cancer using ionizing radiation, they will inevitably get a different cancer from the treatment.
Answer:
Ionizing Radiation: Cause and Cure of Cancer
It may seem contradictory that ionizing radiation can both cause cancer and also be used to treat it. However, the key lies in how radiation interacts with cells and how that interaction is applied therapeutically.
How Ionizing Radiation Affects Cells
- Ionizing radiation damages DNA by:
- Direct ionization of DNA molecules
- Generating free radicals that chemically alter DNA
- Breaking chemical bonds within the DNA strand
When DNA is damaged:
- Severe damage: Cell dies.
- Moderate damage: Cell may repair correctly or incorrectly.
- Incorrect repair: Can lead to mutations → potentially causing cancer.
Why Radiation Can Also Treat Cancer
Cancer cells have unique vulnerabilities:
- They divide more rapidly than normal cells.
- They have defective or inefficient DNA repair mechanisms.
- They are less able to recover from radiation-induced damage.
Radiation therapy takes advantage of these weaknesses by:
- Targeting high-energy radiation at tumors to damage cancer DNA.
- Using fractionated doses—multiple small doses to minimize harm to healthy tissue.
- Allowing healthy cells (with better repair mechanisms) to recover between sessions.
Thus, when delivered precisely and at high enough energy, ionizing radiation kills cancer cells more effectively than it harms normal cells.
Correct Answer:
If the energy of the ionizing radiation is high enough, it will kill cancer cells.