The treatment of cancer by using penetrating beams of high-energy waves or streams of particles to kill cancer cells in a specific area of the body. The radiation used for cancer treatment is generated by specialized machines or radioactive substances that aim specific amounts of radiation at tumors. Radiation at these high dosages kills malignant cells or prevents them from growing and dividing. Because cancer cells grow and divide more rapidly than most of the normal cells around them, radiation therapy can successfully treat many kinds of cancer.
Although normal cells are also affected by radiation, unlike cancer cells, most of them recover from the effects of radiation. To protect normal cells, doctors carefully limit the dosage of radiation and spread out the treatment over time. They also shield as much normal tissue as possible while they aim the radiation at the site of the cancer. The goal of radiation therapy is to kill the cancer cells with as little risk as possible to normal cells.
A radiation oncologist prescribes the type and amount of radiation treatment. The radiation team may include a radiation physicist, who makes sure that the equipment is working properly and that the machines deliver the correct dosage of radiation. The physicist also works closely with the doctor to plan treatment. The dosimetrist works under the direction of a doctor and the radiation physicist in administering the treatment plan by calculating the amount of radiation to be delivered to the cancer and normal nearby tissues. The radiation therapist positions patients for treatments and runs the equipment that delivers the radiation. The radiation nurse coordinates patient care and helps patients learn about treatment and side effects.
The radiation health care team also may include a physician assistant, radiologist, dietician, radiation oncologist, physical therapist, social worker or other health care professional, and radiation nurse.
For early cases of prostate cancer that has not spread, radiation treatment may be offered as an alternative to surgery. External beam radiation treatment is commonly used to treat prostate cancer that has spread too widely in the pelvis to be removed surgically but has not spread to the lymph nodes.
Types of Radiation Treatment
Radiation therapy can be given in one of two ways: externally or internally. Some patients have both, one after the other. Most people have external radiation for the treatment of male reproductive cancer, usually during outpatient visits to a hospital or treatment center. In external radiation therapy, a machine directs high-energy rays at the cancer and a small marginal of normal tissue surrounding it.
The various machines used for external radiation work in slightly different ways. Some are better for treating cancers near the skin surface; others work best on cancers deeper in the body. The most common type of machine used for radiation therapy is called a linear accelerator. Some radiation machines use a variety of radioactive substances (such as cobalt 60) as the source of high-energy rays.
When internal radiation therapy (brachytherapy) is used, the radiation source is placed inside the body to target cancer cells without harming the surrounding tissues. This type of treatment is not often recommended when the cancer has spread beyond the prostate gland. The source of the radiation (such as radioactive iodine) sealed in a small holder is called an implant, which may be thin wires, plastic catheters, capsules, or seeds. An implant may be placed directly into a tumor or inserted into a body cavity; sometimes after a tumor has been removed by surgery, the implant is placed in the area from which the tumor was removed to kill any tumor cells that may remain.
Another type of internal radiation therapy uses unsealed radioactive materials, which may be swallowed or injected into the body. This type of treatment may require a hospital stay of several days. Brachytherapy may be used alone or combined with hormonal therapy or external beam radiation therapy.
Radiation before, during, and after Surgery
Radiation therapy can be used to treat many kinds of male reproductive cancers. Doctors may use radiation before surgery to shrink a tumor, making removal of cancerous tissue easier and allowing the surgeon to perform less radical surgery.
Alternatively, a doctor may choose to combine radiation therapy and surgery at the same time in a procedure known as intraoperative radiation.
Most typically, radiation therapy is used after surgery to stop the growth of cancer cells that may remain.
In some cases, instead of surgery doctors use radiation with chemotherapy to destroy cancer. Radiation may be administered before, during, or after chemotherapy. Doctors carefully tailor this combination treatment to each patient’s needs, depending on the type of cancer, its location, and its size. The purpose of radiation treatment before or during chemotherapy is to make the tumor smaller and thus improve the effectiveness of the anticancer drugs. Doctors sometimes recommend that a patient complete chemotherapy and then have radiation treatment to kill any cancer cells that remain.
In advanced prostate cancer, radiation can help to shrink tumors and relieve pain when curing cancer is not possible. Many cancer patients find that they have a better quality of life when radiation is used for this purpose.
The brief high dosages of radiation that damage or destroy cancer cells can also injure or kill normal cells, producing uncomfortable side effects. Most side effects of radiation treatment are well known and are easily treated; their risk is usually less important than the benefit of killing cancer cells.
Diarrhea and fatigue are common problems, which usually end after treatment is completed. Some men may experience continuing problems such as urinary incontinence and impotence after external radiation; treatments that can help alleviate these problems are available.
Long-term complications are uncommon with brachytherapy. Most men experience some discomfort and temporary urinary incontinence after the implant, and some may experience temporary problems with impotence.