What is radiation therapy?

Radiation therapy, also known as radiotherapy, is a common treatment for cancer where radiation is used to destroy or shrink a tumor. It is often combined with other therapies, such as chemotherapy, surgery, targeted therapy or hormone therapy.

During radiation therapy, high-energy radiation from X-rays, gamma rays, protons or electron beams is used to precisely target tumors. The radiation damages the DNA inside cancer cells, causing them to stop dividing and die. The goal of radiation therapy is to treat a specific part of the body to reduce damage to normal cells.

More than half of people in the United States diagnosed with cancer will have some form of radiation therapy.

female patient receiving radiation therapy

Types of radiation therapy

Your doctor might recommend different types of radiation therapy depending on your cancer diagnosis, what stage it is and your overall health. Radiation therapy can be external, where a machine outside your body targets the tumor with high-energy rays, or internal, where a radioactive source is put inside your body.

How to prepare for radiation therapy

Your care team, including your radiation oncologist (a cancer doctor who specializes in radiation therapy) and other healthcare professionals, will plan your treatment. Your doctor will explain what to expect from treatment, your treatment schedule and possible side effects. You will have a chance to ask questions and raise any concerns.

Your doctor will tell you if you need to do anything, such as stop taking other medicines or follow a special diet. You might also need to talk to your employer about taking time off and ask a family member or friend to drive you to appointments.

It is normal to feel anxious and overwhelmed following a cancer diagnosis. Your nurse navigator can connect you with cancer support services that may help you manage the emotional and physical aspects of your care.

What to expect

Your radiation treatment will take place at an outpatient center or hospital. Before your first appointment, you will have a planning appointment with your care team. You will have a physical exam and, in some cases, imaging tests. 

On the day of the appointment, you should arrive on time and wear comfortable, loose-fitting clothes that are easy to take off if required. Follow any instructions from your doctor about what to eat. If you are having internal radiation therapy, you may need to prepare to stay overnight in the hospital.

Radiation therapy side effects

Radiation can damage healthy cells as well as cancer cells, leading to side effects. These can depend on the type of cancer, treatment and radiation dose. Some people experience many side effects, while others are not affected.

Common side effects are fatigue and changes to your skin after treatment. You might also experience: 

  • Changes in taste
  • Diarrhea
  • Hair loss
  • Headache
  • Fertility problems
  • Mouth problems
  • Nausea and vomiting
  • Sexual problems
  • Skin changes
  • Swelling
  • Throat problems, such as difficulty swallowing
  • Thyroid issues
  • Urinary and bladder problems

Frequently asked questions

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