Radiation treatment is one of the most common and effective ways to destroy cancer cells and shrink tumors. It works by exposing targeted areas to high-energy rays or waves in such a way that the structure of cells is damaged or destroyed.
At Memorial Sloan Kettering, approximately half of our adult cancer patients undergo radiation therapy as a form of primary treatment or as part of a broader approach that includes chemotherapy, surgery, or other modalities. For many cancers, radiation treatment may be all that is needed to eliminate disease.
There are different ways to deliver radiation treatment. With external beam radiation therapy, treatment is delivered from a machine outside the body. With internal radiation (brachytherapy), sealed sources of radioactivity are placed near or within the tumor. Less commonly, radiation treatment can also be administered using liquid materials by mouth or infusion through a vein (systemic radiation).
Although it has been a widely used treatment for decades, confusion and misunderstandings about the safety of radiation treatment persist. We asked Memorial Sloan Kettering Radiation Safety Officer Jean St. Germain to tell us about the concerns she hears most frequently from patients and their families — and what answers and reassurance she provides.
Does receiving external-beam radiation make a person radioactive or able to expose others to radiation?
External-beam therapy does not make a person radioactive in any way. The therapy only affects your cells for the very short time that you are receiving treatment. A person who has received external-beam radiation is unable to contaminate or transfer that radiation to any other person.
How can I be sure that the external-beam radiation machine isn’t damaging normal, healthy tissue in my body?
We have carefully developed methods for calibrating radiation beams and ensuring that they reach the areas they are intended to target. Even when normal tissues near the area undergoing radiation receive small amounts of radiation, it is rare for long-term damage to occur. Our doctors also know how much radiation healthy tissue can receive without causing irreversible damage. We often use special masks, molds, or casts of body parts to keep you absolutely still during treatment, so that we can aim the radiation beams precisely to the area we want to treat.
Is there any risk that internal radiation implants (brachytherapy) will leak or break free from where they are placed and move around my body?
With brachytherapy, we use a needle or a catheter to insert radioactive material contained within an impenetrable sealed source such as a seed, pellet, wire, or capsule. As the radioactive isotopes inside the implant decay naturally over time, they emit radiation and damage nearby cancer cells. This radioactivity travels only a certain distance beyond the implant, and eventually deteriorates to the point that the implant no longer gives off any radiation. The implants are specially tested and sealed to ensure that radioactive material doesn’t leak, and we place them in such a way that it’s highly unlikely they will move. Also, in the case of brachytherapy for genitourinary cancers, while there is no risk that the implants will come out with semen, we do give patients a strainer to use for 24 to 48 hours after the procedure when urinating, in the rare case that a seed becomes dislodged.
Should I limit contact with anyone while brachytherapy implants are inside my body?
Most of our safety concerns are related to being in physical contact with children for extended periods of time, since their bodies are undergoing such rapid change and growth and are therefore more vulnerable to abnormal cell changes. Because we vary the radiation dose in each implant as well as the number of implants we insert based on your particular cancer, we provide you with specific advice about precautions to take when you’re in close contact with children.
Do prostate seed implants put my sexual partner or the person I sleep next to at risk in any way?
Prostate seeds are sealed sources. You cannot contaminate another person by being in his or her physical vicinity, during sexual intercourse, or through any other form of intimate contact. Your doctor or a member of the radiation safety staff will discuss any special precautions you should take with sleep arrangements before you leave the hospital. For example, based on such factors as your age and the age of your partner, for a period of time we may ask that you avoid embracing your partner from the back in the “spooning“ position through the night.
Do I pose a danger to others after receiving radioactive iodine therapy for thyroid cancer?
For several days following this therapy, radioactive substances can be emitted through body fluids such as saliva, urine, and sweat. We send patients home with detailed instructions on how to care for themselves for the first few days — from limiting contact with young children and pets to using separate utensils and towels.
I am having an imaging test using radioactive materials. Will I be radioactive after the test?
Radioactive material will stay in your body for several hours or days depending on the type used and the metabolism of the compound to which it was attached. Eventually, the material decays and your body naturally flushes it out through urine, sweat, and other forms of biological elimination. We make sure the specifics are clear to you before the test, and we may also issue an information card explaining your treatment in the event that you are questioned by someone in airport security, for example.