Anal Cancer: Radiation Therapy

What is radiation therapy?

Radiation therapy is one way to treat anal cancer. It uses X-rays to destroy and control the growth of cancer cells. This is a local treatment. That means it affects the cancer cells only in the area that's treated.

For this treatment, you see a radiation oncologist. This doctor specializes in the use of radiation to kill cancer cells. This doctor decides what kind of radiation you need, how often you need it, and at what dose.

How is radiation therapy used for anal cancer?

It's common to use radiation therapy at the same time as chemotherapy to treat anal cancer. This is called chemoradiation.

Radiation may be given after surgery to kill any cancer cells that may be left in your body.

It might be used to treat anal cancer that has spread to nearby lymph nodes.

If the cancer isn't responding to treatment and is causing problems, radiation can be used to ease symptoms the tumor is causing, for instance, blockages or pain.

Radiation is normally given 5 days a week for several weeks.

What to expect during external radiation therapy

Before you start treatment, your healthcare provider will do imaging scans of your cancer. This is done to measure the exact spot of the tumor so the beams of radiation can be focused there. Your healthcare provider may put small marks on your skin to mark the treatment area. These marks are used to focus the radiation on the tumor, and not healthy parts of your body. A mold or cast might be made to hold you in the exact same position for each treatment.

On the day of treatment, you’re carefully put into the correct position. You may see lights from the machine lined up with the marks on your skin. These help the therapist know the radiation is going to the right place. The machine doesn't touch you during the treatment. You can't see or feel the radiation. It’s a lot like getting an X-ray, but it takes longer.

The therapist will leave the room while the machine sends radiation to the tumor. During this time, he or she can see you, hear you, and talk to you. When the machine sends radiation to your tumor, you’ll need to be very still. But you don’t have to hold your breath. The process will likely take less than an hour.

What are common side effects of radiation therapy for anal cancer?

Radiation affects both normal cells and cancer cells. This means it can cause side effects. Some side effects can be treated. They may even get better or go away over time after treatment ends. Here are some common side effects of radiation for anal cancer:

  • Skin irritation, redness, blistering, itching, or burning in the treated area around the anus

  • Diarrhea, sometimes with some rectal bleeding

  • Discomfort when having a bowel movement

  • Nausea and vomiting 

  • An urgent need to urinate

  • Bladder pain

  • Extreme tiredness (fatigue)

  • Inability to have children (infertility)

  • Impotence (erectile dysfunction)

Working with your healthcare provider

It's important to know how the radiation will work and what side effects you might have. Ask what can be done to help prevent or ease them. Also know which side effects are short-term and which could affect the rest of your life.

Talk with your healthcare team about what signs to look for and when to call them. For instance, radiation for anal cancer can cause diarrhea, bleeding, and other bowel problems. Know what number to call with questions. Is there a different number for evenings and weekends?

It may be helpful to keep a diary of your side effects. Write down physical, thinking, and emotional changes. A written list will make it easier for you to remember your questions when you go to your appointments. It will also make it easier for you to work with your healthcare team to make a plan to manage your side effects.

Online Medical Reviewer: Kim Stump-Sutliff RN MSN AOCNS
Online Medical Reviewer: Lu Cunningham
Online Medical Reviewer: Richard LoCicero MD
Date Last Reviewed: 10/1/2018
© 2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.