Radiation therapy uses high doses of radiation, such as X-rays, to destroy cancer cells. The radiation damages the genetic material of the cells so that they can't grow. Radiation damages normal cells as well as cancer cells. But the normal cells can repair themselves and function, while the cancer cells cannot.
Radiation therapy may be used alone or combined with hormonal treatment to treat prostate cancer. It works best to treat cancers that haven't spread outside the prostate. But it also may be used if the cancer has spread to nearby tissue. Radiation is sometimes used after surgery to destroy any remaining cancer cells and to relieve pain from metastatic cancer.
Radiation therapy to treat prostate cancer can be done in two ways. When it's given from a machine outside the body, it's called external beam radiation, or EBRT. When radiation is placed inside the body, it's called internal radiation, or brachytherapy.
Sometimes treatment combines brachytherapy with low-dose external radiation. In other cases, treatment that combines surgery with external radiation or hormone therapy may be used along with brachytherapy.
Before radiation therapy is scheduled, your doctor probably will order a bone scan and CT scan to find out if the cancer has spread to other parts of your body. If it has, your doctor may offer you the option of a clinical trial for treatment.
Radiation treatments to the prostate can injure the rectum, which is behind the prostate. Your doctor may suggest using a hydrogel spacer. It's a water-based gel. Before you have radiation treatments, the gel is injected into the space between the prostate and rectum. The gel quickly becomes solid, and it stays solid for about 3 months. After that, it dissolves. The spacer shields the rectum from much of the radiation aimed at the prostate.
Types of radiation
Radiation therapy to treat prostate cancer can be done in two ways:
- External beam radiation therapy.
- This uses a large machine to aim a beam of radiation at your tumor. A tiny ink tattoo may be placed on your skin so that the radiation beam can be aimed at the same spot for each treatment. This helps protect nearby healthy tissue from the radiation.
- Internal radiation therapy (brachytherapy).
- This is done with tiny seeds that contain radioactive material. The doctor uses needles to insert the seeds into your prostate. They're placed through the skin between your anus and scrotum (perineum). The doctor uses ultrasound to locate your prostate and guide the needles.
Sometimes prostate cancer is treated with both external and internal radiation therapy.