Radiation therapy (radiotherapy) is the use of high-energy radiation to relieve tumor symptoms, control tumor growth or cure a tumor. Various types of radiation, such as gamma rays, X-rays and charged particles are used to safely and effectively kill cancer cells and shrink tumors. About 50 percent of all cancer patients get some type of radiation therapy at some point during the course of their treatment.
The radiation can be delivered:
- From a radioactive material surgically placed inside the body near the cancer cells (brachytherapy or internal radiation).
- From a machine placed outside the body (external-beam radiation therapy).
- Using radioactive substances, like radioactive iodine, that travel in blood (systemic radiation therapy).
How radiation therapy works
Radiation therapy damages the DNA of cancer cells and destroys their ability to reproduce. DNA refers to the molecules within cells that carry and pass genetic information from one generation to the next. When the DNA of cancer cells is damaged, the cells stop multiplying, die and get broken down and removed naturally from the body. Radiation therapy can damage the DNA of cancer cells directly or by creating free radicals (charged particles) inside the cells. Since normal cells also can be damaged by radiation, potential adverse effects on normal tissue must be taken into account when planning for radiation therapy.
Radiation therapy team
A highly skilled team of medical professionals is usually involved in radiotherapy, working together to deliver the best possible care.
Members of the team include:
- Radiation oncologist: A doctor who specializes in delivering radiation therapy for treating cancer. The doctor works closely with members of the team to develop a treatment plan and oversees the entire treatment process.
- Radiation oncology nurse: A skilled nurse experienced in caring for radiation therapy patients. The nurse answers patient questions about the treatment, monitors patient health during treatment and helps to manage possible side effects.
- Dosimetrist: An expert in calculating the right radiation dose, who helps the radiation oncologist plan and deliver radiation safely and effectively.
- Medical radiation physicist: A professional with know-how in radiation equipment. The physicist helps with designing treatment plans.
- Radiotherapy technologist (radiation therapist): A professional who operates radiation treatment machines and offers scheduled treatments to patients.
- Other professionals: The team may also include a physical therapist, dentist, nutritionist (dietitian) and a social worker. These professionals help with additional emotional, physical and social needs.
What happens before treatment
- Consultation with radiation oncologist
During this meeting, the doctor reviews your medical records, performs a physical exam and recommends tests. The doctor also will inform you of potential benefits and risks of radiation therapy, and give you the opportunity to ask questions.
- Giving consent for radiotherapy
After you decide to undergo radiation therapy, the team will ask you to sign an informed consent form. By signing, you confirm that you have been informed about available treatment options, have chosen to undergo radiation therapy, permit the caregivers to administer the treatment, and understand that the treatment is not guaranteed to deliver the intended results.
- Treatment simulation and planning
The first radiotherapy session is simulation, a practice undertaken without giving actual radiation. The team uses equipment such as a magnetic resonance imaging (MRI), computed tomography (CT) scan or an X-ray to identify tumor location and demonstrate the treatment process. Depending on the location of the tumor, a small mark will be placed on your skin to help the treatment team to aim the radiation beam accurately at the tumor.
You also will be fitted with an immobilization device such as a tape, molds, headrests, foam sponges and plaster casts to help you remain in the same position throughout treatment. If radiation is to be delivered to the neck or head, you may be fitted with a thermoplastic mask (a mesh mask molded to your face and affixed to the treatment table) to hold your head gently in place. If you feel discomfort or anxiety during simulation, talk to the team about it. They care about your comfort and will make the necessary adjustments or offer appropriate medication so you are relaxed during planning scans and treatment. After simulation, the team will review your medical information and develop a treatment plan.
Factors that determine the type of radiation therapy recommended by a radiation oncologist include:
(a) Type of cancer
(b) Size of cancer
(c) Location of the cancer in the body
(d) Patient’s medical history and general health
(e) Closeness of the cancer to normal tissues or cells sensitive to radiation.
(f) Whether radiotherapy will be used with other treatments such as chemotherapy or surgery
(g) How far into the tissue or body the radiation has to travel.
(h) Other crucial factors, such as age of the patient and concomitant medical conditions.
What happens during treatment
- External-beam radiation therapy: Delivers radiation from a machine located outside the body, with each session being quick, painless and lasting around 15 minutes. Usually, patients have 5 treatments sessions each week (Monday to Friday) for 3 to 9 weeks. While radiation is targeted only at the tumor, some healthy tissues surrounding the tumor may be affected, so a 2-day pause is taken every week to allow the body to repair normal tissue damage.
- Brachytherapy (internal radiation therapy): The treatment uses both temporary and permanent radioactive sources placed surgically in the tumor site. The treatment is delivered over many days and weeks and you may have to stay in hospital briefly. You also may require anesthesia to block pain when radioactive sources are placed into the body. There is little to no discomfort during radiation therapy, but you may experience nausea or weakness from anesthesia. To protect other people from radiation exposure, you will need to take precautions until the temporary implant is removed or the permanent implant loses radioactivity.
The radiation oncologist will evaluate how your treatment is progressing at least once every week. When necessary, the doctor will adjust the treatment plan for maximum effect.
You may experience fatigue, emotional distress or skin sensitivity at the site of radiation exposure. Ways you can reduce such problems include:
- Plan for extra rest.
- Seek emotional support.
- Eat a healthy diet.
- Minimize sun exposure.
- Apply skin lotions approved by your treatment team.
Once treatment is concluded, your radiation oncologist will schedule follow-up appointments to monitor your recovery and watch for any delayed side effects. The number of follow-up visits will reduce as your body heals. It is important to ask your doctor for a written record of the treatment that you can use as a valuable resource for your long-term health care.