How does radiation play a role in the treatment of cancer?

Surgery, chemotherapy, and radiation are the three primary means of treating cancer.  Surgery is a local treatment and removes the primary disease. Chemotherapy is a systemic treatment and travels the entire body to give prevent distant disease from occurring and treat residual cancer in the primary site. Radiation is used to provide local treatment to shrink the primary tumor and eliminate microscopic disease. For many cancers, all three treatments are required.

What is Radiation?

Radiation is electromagnetic energy.  Radiation is all around us. We live every day with radiation on us from the sun, electronics, and the soil under our feet.  Radiation used in the treatment of cancer are high energy electromagnetic waves generated from a linear accelerator and focused to a particular part of the body to shrink tumors and kill cancer cells. Radiation may be delivered by a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy, also called brachytherapy). Systemic radiation therapy uses radioactive substances, such as radioactive iodine, that travel in the blood to kill cancer cells.  About half of all cancer patients receive some type of radiation therapy sometime during the course of their treatment. Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells. X-rays, gamma rays, and charged particles are types of radiation used for cancer treatment.

How does Radiation kill cancer cells?

Radiation damages the DNA of cells. DNA is the blueprint for both normal and cancer cells.  DNA provided the instructions for cells to produce protein used to function, grow, and divide. When radiation damages the genes of a cancer cell, the cell is unable to grow and divide any more. Normal cells also have their DNA damaged. However, normal cells are able to repair their DNA better than cancer cells, and thus over duration of radiation treatment, the cancer cells selectively die. Additionally, advance technology to deliver radiation to a precise target in the body reduces the exposure of radiation to surrounding normal cells while focusing the radiation to the target, thereby reducing the harmful effects of radiation to the body while maximizing the killing effect of radiation.

Why do patients receive Radiation Therapy?

Radiation therapy is sometimes given with curative intent (that is, with the hope that the treatment will cure a cancer, either by eliminating a tumor, preventing cancer recurrence, or both). In such cases, radiation therapy may be used alone or in combination with surgery, chemotherapy, or both.

What is palliative radiation therapy?

Radiation therapy may also be given with palliative intent. Palliative treatments are not intended to cure. Instead, they relieve symptoms and reduce the suffering caused by cancer. Some examples of palliative radiation therapy are:
  • Radiation given to the brain to shrink tumors formed from cancer cells that have spread to the brain from another part of the body (metastases).
  • Radiation given to shrink a tumor that is pressing on the spine or growing within a bone, which can cause pain.
  • Radiation given to shrink a tumor near the esophagus, which can interfere with a patient’s ability to eat and drink.

Is there a patient resource book on radiation therapy?

Yes! The National Cancer Institute wrote a freely accessible book called Radiation Therapy and You. The book serves as an excellent resource on what radiation is, how it is delivered, patient feelings during radiation therapy, side effects of radiation, and foods and liquids to avoid during radiation treatment.  You can access it here. (Radiation Therapy and You) Some content used freely with permission from the National Cancer Institute.