Radiation therapy, or radiotherapy

Radiation therapy, also called radiotherapy, is a method of treating cancer in which high-energy rays destroy cancer cells. Most commonly X-rays are used for this purpose, but there are other types of radiation therapy as well, including proton therapy.

Modern radiotherapy techniques are precise. Beams of radiation are aimed directly at the cancer cells while protecting healthy tissues from high doses of radiation.

It can be applied either inside the body or from outside. The most common form is external beam radiation therapy. This treatment uses a large machine called a linear accelerator. High-energy beams are directed from the machine, which moves around your body, to a specific point — precisely where the tumor is located.

Internal radiation treatment is also called brachytherapy, which is another common cancer treatment. In this therapy the treating physician places a small solid implant into or near the tumor. Various radioactive isotopes are used (most commonly Ir-192 iridium); once placed into the area to be irradiated, the radioactive emission and its cell-killing effect form the basis of the therapy.

Radiation therapy damages cells by destroying their genetic material. Genetic material controls cell growth and division. During treatment healthy cells can also be harmed along with cancer cells, but healthy cells are generally better able to regenerate than cancer cells. The aim of radiotherapy is to minimize damage to healthy cells during cancer treatment.

When is radiotherapy used?

It is used to treat almost every type of cancer. In fact, more than half of cancer patients receive radiation therapy as part of their treatment. It can also be used to treat some non-cancerous conditions, including so-called benign tumors.

How radiotherapy is used in cancer patients

It may be used at different times or for different reasons during your cancer treatment.

Your care team may recommend radiation therapy in the following situations:

• As the sole treatment for the cancer. This is called primary treatment.
• Before surgery, to shrink the tumor. This is called neoadjuvant therapy.
• After surgery, to stop the growth of any remaining cancer cells. This is called adjuvant therapy.
• Together with other treatments, such as chemotherapy, to destroy cancer cells.
• To relieve symptoms caused by advanced cancer.

Risks of radiotherapy

Radiation treatment can have side effects, but you may hardly notice them. This depends on which part of your body is irradiated and how much radiation is used there. If side effects do occur, they can generally be managed during treatment. Most side effects go away after therapy.

The treated body area and its common side effects:

• Any body area: hair loss (sometimes permanent) and skin irritation at the treatment site, fatigue.
• Head and neck: dry mouth, thicker saliva, difficulty swallowing, sore throat, changes in taste, nausea, oral pain, tooth decay.
• Chest: difficulty swallowing, cough, shortness of breath.
• Abdomen: nausea, vomiting, diarrhea.
• Pelvis: diarrhea, bladder irritation, frequent urination, sexual dysfunction.

Sometimes side effects can develop after treatment. These are called late effects. Very rarely, lymphedema may develop years later. This can be caused by scarring or other damage to lymphatic vessels from the radiation. Ask your treating physician about possible short- and long-term side effects after therapy.

Preparations

Radiation therapy is directed by a physician specialized in this treatment type, the radiation oncologist.

If you agree to radiation treatment, your care team will carefully plan the therapy. They will determine the exact location that needs to receive the right amount of radiation for your recovery. They will decide on the type and dose of radiation. This is based on the type of cancer, your overall health condition, and the treatment goals.

Planning is important so that the dose and focus of the radiation beams are correct. If this is precise, healthy cells around the tumor are less likely to be damaged.

What to expect

For external radiation therapy a machine is used that directs high-energy rays into your body; this is called a linear accelerator.

While you lie still, the linear accelerator moves around you. It delivers radiation to the tumor from multiple angles. The device is set up by the treatment staff according to your needs so that the precise dose of radiation reaches a specific point in your body. You do not feel the radiation itself; it is similar to having an X-ray taken.

External radiation is an outpatient treatment. That means you usually do not need to stay in the hospital after the session. Typically you receive treatment five days a week for several weeks, although some courses last only 1–2 weeks. Treatments are spread out so that healthy cells have time to recover between sessions. Sometimes treatment is a single session to relieve pain or other symptoms of more advanced disease.

Each session lasts about 10–30 minutes. Most of that time is spent ensuring your body is held in the correct position.

The linear accelerator makes a humming noise. It may also rotate around you to reach the treatment area from different angles.

The radiotherapy team is located in a nearby control room. You can communicate with them via the video and audio system connecting the rooms. Although radiation does not cause direct pain, be sure to tell them if you feel uncomfortable.

Results

After radiotherapy imaging tests may be done to see whether the tumor is shrinking. Sometimes the tumor responds immediately to treatment, while other times it may take weeks or months for changes to be noticeable. Ask your radiotherapy team what to expect and what results are likely.