Radiation therapy uses invisible, high-energy radiation to destroy cancer cells. There are two main types of radiation therapy used in prostate cancer treatment: external beam radiation and internal radiation therapy, often called brachytherapy. External beam and internal radiation therapy differ in the way the radiation is delivered to a tumor. Whether a prostate cancer patient receives external or internal radiation therapy generally depends on several factors, including the type, size and location of the tumor.
External beam radiation therapy (EBRT) is the most common type of radiation therapy used for cancer treatment. In this type of treatment, a special X-ray machine called a linear accelerator generates and aims radiation at tumors in the body. The patient lies on a bed beneath the machine, and the beam is directed at the cancer site.
Because the prostate may move during radiation treatment as a result of breathing and normal movement in the intestines, healthy tissue near the prostate may be affected. New technologies, such as the TrueBeam™ advanced linear accelerator that targets tumors with high precision, are designed to reduce the amount of radiation healthy tissue receives. TrueBeam is often used in conjunction with the Calypso® 4-D localization system with Beacon® electromagnetic transponders, allowing the robot to reach specific tissue and monitor the position of the prostate during each treatment session. In most cases, EBRT may be delivered to a patient in several sessions over the course of a few weeks.
The following are EBRT techniques we commonly use in the treatment of prostate cancer:
IMRT may be a treatment option for patients with prostate cancer that has not spread. The therapy may also be an option for patients with recurrent prostate cancer who have received radiation therapy for their cancer in the past.
Internal radiation therapy, or brachytherapy, involves placing a radioactive source or isotope—in the form of wires, seeds or rods—inside the body close to the tumor. For prostate cancer, the radioactive source is implanted inside the prostate gland. In some cases, internal radiation therapy is used in conjunction with EBRT. When both forms of radiation therapy are used to treat prostate cancer, EBRT works to destroy cancer cells in the area surrounding the organ while internal radiation therapy delivers a high dose of radiation to the tumor inside it.
The two main types of internal radiation therapy treatments differ in the rate at which radiation is delivered. These two types are:
The SpaceOAR® System may also be incorporated during radiation therapy for prostate cancer to reduce the radiation dose to the rectum. SpaceOAR is a temporary, injectable gel that creates about a half-inch (or 1.3 cm) of space between the prostate and the rectum. The gels stays in the body for about three months, and then is naturally absorbed and eliminated from the body in the urine. By separating the prostate from the rectum and reducing radiation exposure, the gel is designed to reduce, or possibly eliminate, damage to the rectum and associated side effects.