What is radiation therapy?
Radiation therapy uses high-energy rays to kill or shrink cancer cells, and to decrease their ability to divide. Radiation is often used to treat prostate cancer that is still confined to the prostate gland, or has spread only to nearby tissue. If the disease is advanced, radiation may be used to reduce the size of the tumor and to provide relief from symptoms.

What are the types of radiation therapy?

There are generally two types of radiation therapy:

• external beam radiation therapy - a procedure that is similar to having an x-ray, but for a longer period of time. The x-ray beams are directed at the cancer from outside the body.
• internal radiation therapy - a procedure that uses small, radioactive pellets (each about the size of a grain of rice) that are implanted directly into the cancerous prostate tumor. The implanted pellets may be left in permanently or may be only temporary. The pellets emit small amounts of radiation for a period of weeks or months.

What are side effects of radiation therapy?

Side effects, and the degree to which they are experienced, differ. Discuss any possible side effects of treatment with your physician prior to the procedure. Possible side effects of radiation for prostate cancer may include the following:

• diarrhea, with or without blood in the stool, and colitis
• problems associated with urination
• a degree of impotence (inability to achieve or maintain an erection), which may occur within two years of radiation therapy