How does radiation therapy work?

The radiation changes the DNA makeup of the tumor, causing it to shrink or die. Normal cells are able to repair themselves, but cancer cells cannot. Doctors target the radiation to protect healthy cells as much as possible.

When is radiation therapy used?

Sometimes radiation therapy is the only treatment a patient needs. At other times, it is only one part of a patient’s treatment. Radiation therapy is used:
  • As the only (primary) treatment for cancer
  • Before surgery, to shrink a cancerous tumor
  • After surgery, to stop the growth of any remaining cancer cells
  • In combination with other treatments, such as chemotherapy and other systemic therapies, to destroy cancer cells

Radiation therapy can also be used in advanced cancer to shrink the tumor. This helps alleviate symptoms caused by the cancer. Radiation therapy is also used in advanced cancers to shrink the tumor and alleviate pain.

Types of Radiation Therapy

Image-Guided Radiation Therapy (IGRT)

Because tissues and organs can settle around bones differently each time a patient lies down on a treatment table, tumors can end up in different positions from one treatment session to another. 

Image-guided radiotherapy uses X-rays to verify the tumor position in your body. This means the radiation can only target the tumor and spare healthy tissue.

How long is radiation therapy?

The number of treatments you have will depend on your type and stage of cancer. Because your cancer is unique, your treatment plan will be too, including the duration and intensity of radiation therapy treatment. On average, a course of treatment may last 2 to 10 weeks.

Each external radiation treatment is quite short—only about 20 minutes, with the actual radiation only taking a minute or two.

Your Team at Intermountain Cancer Center

Every patient and every cancer is different. Every treatment plan is also different. Your cancer treatment is always based on National Comprehensive Cancer Network (NCCN) guidelines and your specific pathology.

Radiation oncologists are part of your treatment team. They work with your oncologist and surgical specialists to determine the best treatment plan for you. The radiation team also includes the physicist, dosimetrist, radiation therapists

What to Expect During Radiation Therapy

Before Therapy

  • Your doctor will explain your treatment plan, possible side effects, and how the treatments may help.
  • You’ll have a physical exam and tests to pinpoint the exact location of the cancer.
  • Small tattoos may be placed on your skin to show the technicians where to aim the radiation. The tattoos are tiny—about the size of a pinhead.
  • You may also be fitted for an immobilization device. Doctors use tape, headrests, molds, or plaster casts to help support the body part requiring treatment. This helps you stay in the same position throughout treatment.

During Therapy

  • You’ll sit in a chair or lie on a table. A technician may use your immobilization device or other pieces of equipment to help hold you in position for the treatment.
  • The radiation therapist will then go into the next room to control the machine. The therapist can see and hear you. The therapist can talk to you through a speaker.
  • You will see lights. These show the therapist exactly where to point the radiation. The arm of the linear accelerator will move above and around you as it delivers the radiation.
  • You will need to lie as still as possible while the radiation beam is on.

Side Effects of Radiation Therapy

Side effects usually start about 3 weeks into treatment. Side effects can last for a few weeks after radiation therapy ends. They usually get better once radiation therapy is complete.

Many of the side effects of radiation therapy only happen in the area being treated. For example, a breast cancer patient may notice skin irritation, similar to a mild to moderate sunburn, while a patient with cancer in the mouth may have soreness when swallowing.

Most Common Side Effects

  • Fatigue

    Feeling very tired or worn out is one of the most common side effects of radiation therapy. To fight fatigue, try to get at least 8 hours of sleep every night. Plan for short rest times during the day, and especially on weekends when you might have fewer responsibilities. Light exercise or walking can also help keep your energy up.

  • Skin changes

    Radiation therapy can give the skin in the treated area a mild-to-moderate pink color, like with a sunburn. You may have other symptoms, such as soreness or dry skin in the treatment area. Do not rub, scrub, or scratch your skin. Protect it from the sun. Your healthcare provider may recommend creams and ointments to help with irritation.

  • Low blood cell counts

    If the treatment is in an area with a higher density of bone marrow, radiation therapy can lead to a lower blood cell count. This can cause anemia or make it easier for you to get infections. Your doctor may check your blood regularly, especially before any treatments.

  • Hair loss in the body part that is treated

    Unlike chemotherapy, radiation therapy does not lead to generalized hair loss. However, you may lose hair at the site of your radiation treatment. It can take three to six months for the hair to grow back after radiation therapy has ended. In some cases, the hair may not grow back.

    Radiation therapy will not affect the hair on your head unless the treatment focuses on that area.

Poor Appetite

Radiation therapy can take away your desire to eat. However, your body needs food to fuel the healing process. Eat whatever sounds good, whenever you are hungry. A nutritional consult can be arranged for you and you will receive advice and education from your radiation team as well.

Other Side Effects

Radiation treatments can also be overwhelming mentally and emotionally. Talk to your team at Intermountain Cancer Center about tools to help with the anxiety and stress of your treatment. Often, something as simple as meditation, creative therapies, or talk therapy can work extremely well. Be sure to document side effects you experience so your care team can help manage them.

Nutrition During Radiation Therapy

To combat weight loss, we recommend a power-packing diet, which increases the amount of calories and protein in your food without increasing the amount of food you need to eat. The easiest way to power pack is to add fat and carbohydrates (sugar) to food you already eat.

What you can do

Drink fluids 30 to 60 minutes before or after meals, but not at mealtime. Fluids taken with meals can limit available stomach space for food and make you feel full.

Small, frequent meals (6 to 8 times per day) can be easier to manage than 3 large meals.

Use color and variety and creativity to make meals more appealing.

Have nutritious snacks readily available to eat when you are hungry.

Light exercise (per physician approval) before a meal may help increase appetite.

Take advantage of the times when you feel hungry by eating.

Eat your favorite foods at any time of the day.

Managing Fatigue During Radiation Therapy

Light exercise can help improve your energy levels. Even just a 30 minute walk every day can help both your fatigue and your mental health. If you don’t have enough energy for 30 minutes of exercise in a day, try taking 3 walks that day for 10 minutes each.

Check with your medical team for specific exercise recommendations. And always listen to your body. Don’t exercise if you are not feeling well or running a fever.

What to expect after radiation therapy

Your energy levels will most likely be lower after a radiation treatment. Be sure to stay hydrated and eat whatever foods sound good. Maintaining nutrition will help with your overall energy.

Try to pace yourself in your daily activities. After you complete a task, you will probably need to rest. While it can be frustrating, fatigue is one of the most common side effects of radiation therapy. It can help to remember it is only temporary.

Radiation Therapy vs. Chemotherapy

Radiation therapy involves giving high doses of radiation beams directly into a tumor. The radiation changes the DNA makeup of the tumor, causing it to shrink or die.

Chemotherapy uses drugs to target and kill rapidly dividing cancer cells. The treatment is delivered through an infusion into a vein in or medication port, or it can be taken orally.

Your medical team at Intermountain Cancer Center will recommend which therapy (or sometimes both) to use in order to treat your cancer.

Frequently Asked Questions

Can you work during radiation therapy?

Radiation therapy is usually well tolerated and many patients are able to continue their normal routines. Some patients may notice they’re more tired than usual, which can affect how you need to plan your workday. Talk with your doctor, nurse navigator or care team about your plans. They can advise you and give you any documents your employer may need.