Radiation is a very important tool in cancer treatment, and it’s used mainly through a technique called radiation therapy (or radiotherapy). The idea is to use high-energy radiation to damage the DNA of cancer cells, which prevents them from dividing and growing. Since cancer cells are often less able to repair DNA damage than healthy cells, they are more likely to die from radiation exposure.
Here’s a breakdown of how it works:
Methods of Radiation Therapy
- External Beam Radiation Therapy (EBRT)
- The most common type.
- A machine (linear accelerator) directs high-energy X-rays, gamma rays, or proton beams at the tumor from outside the body.
- Modern techniques (like IMRT or proton therapy) shape and focus the beam to minimize damage to healthy tissue.
- Internal Radiation Therapy (Brachytherapy)
- Radioactive material (like tiny seeds or wires) is placed inside or very close to the tumor.
- Delivers a high dose directly to the tumor while limiting exposure to surrounding healthy tissue.
- Often used in prostate, cervical, and breast cancers.
- Systemic Radiation Therapy
- Radioactive substances (such as radioactive iodine, I-131) are swallowed or injected into the bloodstream.
- They travel throughout the body but accumulate in cancer cells.
- Useful for certain cancers like thyroid cancer or bone metastases.
Why Radiation Works
- Radiation damages DNA inside cells.
- Cancer cells:
- Multiply quickly.
- Have less efficient DNA repair mechanisms.
- Are therefore more likely to be destroyed by radiation.
- Normal cells can also be affected, but they usually repair themselves more effectively.
Goals of Radiation Therapy
- Curative treatment → to completely destroy a tumor.
- Adjuvant therapy → used with surgery or chemotherapy to kill remaining cancer cells.
- Palliative treatment → to shrink tumors and relieve pain or symptoms (not necessarily to cure).
Side Effects
Because healthy tissue around the tumor may also be exposed, patients may experience:
- Fatigue
- Skin irritation or burns (at the treated area)
- Hair loss (only in treated area, not whole body)
- Nausea, difficulty swallowing, or diarrhea (depending on the site)
- Long-term effects, such as fibrosis or secondary cancers, are rare but possible.
In short: Radiation therapy uses carefully targeted energy to damage the DNA of cancer cells. It can be applied from outside the body, inside the body, or systemically, and plays a crucial role in curing, controlling, or easing the symptoms of cancer.