Related topics: •  Breast Cancer Surgery •  Chemotherapy and Side Effects •  Immunotherapy for Cancer

If you’ve ever had a sunburn, you already know high-energy rays can be damaging. Radiation therapy uses the same principle -- the power of high-energy waves or particles -- to destroy cancer cells in a targeted way. Cells are more vulnerable when they are dividing rapidly, so radiation destroys cancer cells while causing relatively less damage to cells that are not dividing fast.

Unlike chemotherapy drugs that affect all cells -- both healthy and cancerous -- throughout the body, radiation can target specific tumors. Because doctors can steer clear of healthy organs, radiation may have fewer side effects than chemotherapy. About half of all cancer patients receive some form of radiation as part of their treatment plans.

Cancer cells have mistakes, or mutations in their DNA that enable them to keep dividing out of control. It's widely believed that radiation therapy (or radiotherapy) works by further damaging the DNA of cancer cells by physically breaking it up. That way, the genetic instructions can't be read by the cell any longer and it will stop replicating. New research using mice shows that radiation may also work by destroying the blood vessels that feed the tumor cells.

Some types of tumors are more sensitive to radiation than others. Radiation therapy is commonly used to treat many different types of cancer, including cancer of the lungs, breast, prostate, colon, and skin. It’s often combined with chemotherapy or surgery.

At the very least, radiation should be able to slow a tumor's growth. In many cases, the goal is much more ambitious: A complete cure. The potential benefits of radiation therapy depend on the type, size, location, and extent of the cancer. An oncologist may work with a specialist (called a radiation oncologist) and other members of your health-care team to figure out a specific treatment plan, including the type of radiation and the dosage. Discuss your treatment goals with your doctors.

There are two major types of radiation therapy: external and internal.

External therapy is the most common approach, and that means the source of the radiation -- usually a machine -- is outside of the body and delivers a beam of radiation to the affected area. The beam usually consists of high-energy electromagnetic rays, such as x-rays or the even more powerful gamma rays (produced by the breakdown of certain radioactive materials).

Some facilities also use particle beams made of subatomic particles, most commonly protons (positively charged particles). Particles typically cannot penetrate as far into the body as electromagnetic rays, and are mainly used to treat cancers in delicate locations, such as the brain.

Internal radiation therapy is another important tool. In this procedure, the radioactive material may be injected into the body, or placed in sealed containers and deposited there surgically.

In one form of internal therapy, a doctor puts a tiny amount of radioactive substance right next to the tumor or inside it, an approach that’s also called brachytherapy. This procedure is sometimes used to treat cancers of the prostate, ovaries, and other places that are hard to reach with external radiation without causing side effects. Brachytherapy can be either low-dose or high-dose, and may involve a short stay in the hospital. Some types of low-dose therapy, usually for prostate cancer, involve tiny "seeds" left in for weeks, months, or permanently.

In another version of internal therapy, a radioactive substance is injected into the bloodstream. This approach, also called systemic radiation therapy, can be an effective treatment for some blood cell cancers such as non-Hodgkin lymphoma.

If you’re undergoing radiation therapy, you’ll get more radiation over a longer period of time than you’d ever get from an x-ray machine. In a typical external radiation treatment plan, you would receive radiation five days a week for one to eight weeks or more. Each treatment session lasts about 15 to 30 minutes.

If you have surgery, you may also receive a single dose of radiation during surgery. After a surgeon has removed as much cancer as possible, radiation is used while the area is easy to access and damage to surrounding tissue can be minimized.

On the other hand, if you're receiving radiation internally, your treatment will depend on the type of radiation that your doctor has planned.

High-dose therapy usually involves outpatient treatment, ranging from a one-time visit to a series of one or two daily sessions for days or weeks. During a session, the radioactive material is placed inside your body through a tube or other device for anywhere up to 20 minutes. However, for some tumors, high-dose therapy may need to stay in place for several days, which would require a stay in the hospital.

Low-dose therapy with implants often involves staying in the hospital for a few days to minimize the radiation exposure to other people.

Long-term implants may be placed once surgically and removed later, or even left in permanently. Compared to materials like uranium, the radioactive materials used for this purpose degrade quickly (usually in a few months) so over time, the level of radioactivity will decline.

Radiation therapy generally doesn’t cause as many side effects as chemotherapy, but it’s still a serious treatment. You may feel severe fatigue for some weeks after therapy, but your energy should return. You’re likely to lose hair temporarily in the area where you were treated. Any patch of skin that’s hit by radiation may become red, painful, dry, and itchy -- the medical version of a sunburn. After a few weeks, the skin may flake or peel, and it may also become extremely sensitive.

There are a number of ways to minimize these unpleasant side effects. It's important to get enough rest and follow a healthy diet. Also, talk with your doctor about controlling pain, nausea, or depression. Finally, try reducing stress through deep breathing, meditation, prayer, reading, or any other activity that gives you a feeling of peace.

If you received external radiation, avoid rubbing, scrubbing, or applying adhesive tape to treated skin. Wear loose cotton clothing, and avoid applying heat or cold packs to the area. Most skincare products (like aftershave or hair-removal products) will probably be too harsh to use on treated skin, and you'll need to protect skin from the sun for at least a year after treatment. Talk with your doctor before using any particular soaps, lotions, medicines, or talcum powder on skin that's been treated, and ask for your doctor about tips for soothing hypersensitive areas. People who have received radiation in the pelvic area, for example, may find it easier to sit on a smooth leather chair rather than ones with patterned fabric.

If your head or neck were treated, common side effects include dry mouth, sore throat, difficulty swallowing, soreness in the jaw, nausea, earache, and changes in the way food tastes. You may also lose your appetite for a while, especially if you received radiation in the mouth or abdomen. It's often helpful to avoid spices, alcohol, tobacco, sugary snacks, and coarse foods such as raw vegetables and crackers. Also, rinse your mouth with warm salt water every hour or so, and moisten food with gravy or sauces to make them easier to swallow. You should also brush your teeth and gums with a very soft-bristled brush, use unwaxed dental floss once daily, and rinse your mouth with cool water after you brush.

Radiation for the abdomen can cause diarrhea, upset stomach, and nausea. If the pelvic region was targeted, side effects may include diarrhea, urinary problems, and impotence or other sexual problems in both men and women. Most of these symptoms should improve shortly after your treatment ends.

Long-term effects of pelvic radiation can include infertility in both men and women, so if you're planning to have children in the future, discuss your options with your doctors. You can also talk with your doctor about how to lessen side effects for the particular form of radiation that you're getting. Visit the Web site of the American Cancer Society for additional tips.

Many patients worry that radiation therapy will make them radioactive. If you’re receiving external radiation, there’s absolutely no cause for concern about becoming radioactive from exposure to the radiation. Your body won’t be emitting any rays or particles that could be harmful to anyone else. Similarly, after high-dose internal treatment, the radioactive material is removed from the body and you should be no risk to others.

If you have a radioactive implant, either short-term or long-term, you will give off some radiation but it won’t travel far beyond your body. The exact distance will depend on the location of the implant and the type of radioactive material used. Your doctor may recommend that you not get too close to pregnant women or young children. If you're staying in the hospital, children and pregnant women may not be allowed in your room, and visitors may need to sit a safe distance away and limit their daily time with you.

If you're getting systemic treatment, the radiation isn't contained in an implant and spreads all through the body. You may give off some radiation, and radioactive particles will leave your body through your urine, saliva, sweat, and other body fluids. You may need to take special precautions when using the toilet, doing laundry, or having any type of intimate contact with others.

You may be aware that x-rays and other types of radiation can actually cause cancer in high doses, so it’s natural to wonder if your radiation treatment might actually be dangerous. In fact, radiation therapy does carry some long-term risks and can actually start a new case of cancer. For example, women who receive radiation for breast cancer are more likely to develop cancer of the esophagus in later years. Men who receive radiation therapy for prostate cancer are at greater risk for rectal cancer, and are encouraged to get regular screening for the disease.

With newer ways of delivering radiation, including 3D radiation therapy and intensity-modulated radiation therapy, less of the surrounding tumor is damaged and your long-term side effects may be lower. But if your doctor recommends radiation, it's because the benefits will most likely outweigh the risks.

-- Chris Woolston, MS, is a contributing editor to Consumer Health Interactive. A former staff writer for Hippocrates magazine, he has written for Health, Hippocrates, and other journals, and writes The Healthy Skeptic, a biweekly column in the Los Angeles Times. He is also the co-author of Generation Extra Large: Rescuing Our Children from the Epidemic of Obesity (Perseus paperback, 2006).

References

Radiation Oncology. Newark Beth Israel Medical Center. http://www.sbhcs.com/hospitals/newark_beth_israel/mservices/oncology/radiation.html#3d

First published December 11, 2008
Last updated December 3, 2009
Copyright © 2008 Consumer Health Interactive

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