Radiation is used to kill tumors, control tumor growth, and relieve pain

Hearing the word “radiation” may prompt many questions and concerns for people with cancer and their families. Radiation is used to kill tumors, control tumor growth, and relieve pain. More than 50% of people with cancer undergo some type of radiation treatment. Although general information can be found on the Internet, your doctors are the most knowledgeable about your medical history, your type of cancer, and your recommended cancer care plan. In other words, your doctor is your best resource for discussing and understanding what type of radiation, if any, is best for treating your cancer.

What is Radiation?

Radiation, which is often described as “moving packets of energy,” refers to a specific type of high-energy electromagnetic radiation used in cancer treatment. According to Charles A. Enke, MD, Professor and Chair, Department of Radiation Oncology with the University of Nebraska Medical Center in Omaha, microwave energy and visible light are some examples of lower-energy electromagnetic radiation. The difference in radiation types depends on their frequencies. Only radiation of the highest frequencies, called ionizing radiation, is capable of damaging living tissue. Although ionizing radiation can be in the form of UV rays, which cause sunburn, and x-rays, which allow visualization of internal body structures, higher intensity radiation can penetrate cells and interfere with their function. This is the type used in cancer treatment. The higher the intensity, the deeper the radiation beams can penetrate.

“Radiation used in cancer therapy has the ability to break chemical bonds that hold molecules together,” explained Dr. Enke. “Radiation therapy works by damaging the DNA molecules within the cancer cell. This results in the death of the cancer cell or prevents the cancer cell from being able to multiply.” The dead cancer cells are naturally eliminated from the body. Although healthy cells are also damaged during radiation, these often have the ability to repair themselves and function normally.

Several types of radiation are used in treating cancer, including external-beam radiation therapy, brachytherapy, and systemic radiation therapy.

External-Beam Radiation Therapy 

Dr. Enke explained that radiation may be mechanically produced by a linear accelerator, or LINAC, which is a machine that produces x-rays and electron beams. This machine directs focused beams of high-energy radiation specifically at tumor cells. 

So the radiologist can define the exact area to deliver radiation (and therefore give you the most precise treatment), you will go through a process called simulation. In simulation, your radiation therapist uses either x-rays or CT scans to pinpoint the area, or “field,” to be treated. to avoid irradiating normal tissue as much as possible. To ensure that the radiation beams are aimed accurately, this process may include making molds or casts of specific parts of your body to position them the same way for each treatment and help you hold them still. Your doctor may also mark your treatment field with small ink dots or tattooed freckles. These may fade but are needed to help define the specific area during your treatment.

Although the treatments themselves are most often painless---much like going for a regular x-ray---side-effects are possible. The treatments can be performed on an outpatient basis and usually only require short visits. The radiation treatment itself usually only takes a few minutes, but appointments often take up to about a half hour because of time spent preparing the equipment and positioning you correctly.

There are several specific external-beam radiation therapies that your doctor may discuss with you if they are right for treating your cancer. These include 3-dimensional conformal radiation therapy, intensity modulated radiation therapy, conformal proton beam radiation therapy, intraoperative radiation therapy, and stereotactic radiosurgery.

Brachytherapy

With internal radiation therapy, or brachytherapy, radioactive material is implanted directly into cancerous tissue. Rather than having radiation beams directed from outside your body, the radiation material is contained within a source, such as a capsule, seed, or tube, which is placed very near or directly inside the cancerous tissue. This allows a higher dose of radiation to be delivered to a smaller area.

These containers are inserted in your body through a tube applicator, or catheter. The procedure is performed in an operating room and requires you to have anesthesia (local or general, depending on the location of the cancer).

Some implants are permanent, while others are temporary. However, permanent implants stop giving off radiation after a certain amount of time, and then remain inactive in your body; they do not need to be removed because they cause no harm.

Talk to your doctor about any special precautions you may need to take and about the type and duration of implant recommended for your particular cancer. 

Systemic Radiation Therapy

Unlike externally applied radiation and implanted radioactive devices, systemic radiation is injected or swallowed in liquid form. These substances are designed to travel through your body and collect in the area where the tumor is located, where the radiation then kills cancer cells.

Your doctor will discuss whether this treatment is right for you, and will inform you of any necessary precautions depending on the substance used, because some radiation usually stays in your body for a few days after treatment.

Side Effects

As with any treatment, side effects vary among people, depending on your overall health, the type and location of the cancer, and the type, dosage, and duration of treatment. Dr. Enke said side effects from radiation can be divided into 2 categories: acute (early) and late side effects. Early side effects usually occur shortly after treatment and are temporary. Common temporary side effects include fatigue, mild skin redness or tanning, and mild decreases in blood counts. For information about dealing with cancer-related fatigue, see the article on Fighting Cancer Fatigue. Late side effects develop over time, and are often permanent. Late effects of treatment and a guide for follow-up care are discussed in Taking Charge of Follow-Up Care. Also see Safety in Radiation Therapy, which addresses concerns you may have about receiving radiation. 

A. Bapsi Chakravarthy, MD, Program Director, Radiation Oncology with Vanderbilt University in Nashville, Tennessee said side effects are often determined by the area of the body treated. “It’s important to have an open dialogue with your doctor to talk about what short-term and long-term effects of radiation can be,” Dr. Chakravarthy said. “Often, the side effects are site specific and will vary.” To learn more about your specific cancer and the possibly side effects of particular treatments, see NCCN Guidelines for Patients or Treatment Summary for your cancer.

Jeffrey Bradley, MD, S. Lee Kling Associate Professor of Radiation Oncology with the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis, Missouri said the anticipated side effects are primarily related to the organs in the body that are directly in the path of the radiation beam. “For example, for a cancer of the throat, the anticipated side effects would be skin redness in the neck region, hoarseness, and sore throat that start during the mid to latter part of radiation treatment,” Dr. Bradley said.

According to Dr. Bradley, some site-specific side effects of radiation therapy include:

• Chest: Cough, pain on swallowing, skin redness, and fatigue
• Abdomen: Nausea, diarrhea, and fatigue
• Pelvis: Diarrhea, more frequent urination, and fatique
• Brain: Hair loss, scalp redness, lower blood counts, nausea, and fatigue

Many medications, therapies, and other methods are available to alleviate or reduce symptoms associated with radiation therapy. Particular therapies depend on each individual's circumstance. Make sure to discuss the options with your physician.

Undergoing Radiation Treatment for Cancer

Radiation therapy is frequently given as a series of daily treatments that can last from 1 to as much as 9 weeks. Patients may need time off or to alter schedules to allow for these daily treatments. However, because the treatments often require only short visits and often do not cause physical discomfort, patients can often work appointments into their normal routine with minimal disruption. Patients are often assisted by a caregiver during their treatment periods; information for these caregivers is provided in For Caregivers: Offering Support During Radiation Treatment.

Make sure you understand the treatment your doctor recommends, as well as the side effects and the impact treatment may have on your life.