How Does Radiation Therapy Work?

Basic Information About Radiation That Everyone Should Know

Patient undergoing radiation oncology treatment
Patient undergoing radiation oncology treatment. Getty/Stone/Lester Lefkowitz

Just how does radiation therapy work? First off, you should know that radiation therapy is one of the most common methods used to treat prostate cancer. Thousands of men each year undergo radiation treatments for their cancer.

The Basics of Radiation Therapy

Radiation is essentially an invisible, high-energy beam. Radiation that is used for cancer treatment is usually a form of high-energy x-ray. Other, less common forms of radiation use particles such as protons to kill cancer cells.

How Does Radiation Kill Cancer Cells?

Radiation works in two ways to kill cancer cells. First, the energy that makes up the radiation directly damages the DNA of any cells that it hits. It damages DNA in such a way that the cell is no longer able to divide and grow, thus, it eventually dies.

Second, the radiation ionizes (in a sense, “charges up”) water molecules near the cancer cells. This results in the creation of “free radicals,” which then also damage the nearby DNA.

Does Radiation Damage Healthy Cells, Too?

Yes. Radiation causes the same damage to healthy cells as it does to cancer cells. A couple of important differences exist, however.

First, cancer cells are, by definition, abnormal and usually have abnormalities that make them more susceptible to the damaging effects of radiation. Healthy cells, in general, are more able to repair the damage that is done to their DNA.

Second, technology exists today that allows the radiation oncologist (the physician who determines how radiation will be given) to better pinpoint the radiation onto only the cancerous tissue.

With sophisticated technology, radiation can be directed at only those tissues that need to be treated. While there is still some scatter of the radiation into other tissues, the majority of the radiation can be precisely given to the cancerous areas.

How Is Radiation Given?

Radiation can be delivered in two primary ways:

External Beam Radiation Therapy: Just as the name suggests, this type of therapy is given outside the body. A large machine produces a beam of high-energy x-rays from outside the patient that is then collimated (or directed) at the part of the body that requires treatment.

The patient lies still on a table while the radiation is delivered. One treatment lasts only a few minutes. Many treatments are typically needed over the course of weeks to complete radiation therapy for prostate cancer.

Brachytherapy: Brachytherapy involves a source of radiation being implanted into the body. The source is placed either directly into or very near the tissue that requires treatment. Prostate cancer is one of the cancers that is most commonly treated in this way.

Tiny radioactive rods, or “seeds,” are implanted directly into the prostate using this form of radiation therapy. These seeds then emit radiation into the nearby tissue. Exactly how many seeds are used and where they are positioned in the prostate is decided by the radiation oncologist.

Does Radiation Hurt?

During the few minutes when you are receiving the radiation treatment, you should feel no pain at all. However, following treatment, many radiation therapy patients develop soreness at the site of treatment.

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