Radiation Therapy for Rectal Cancer
Overview
Radiation therapy works by using high-energy X-rays to kill cancer cells or tumors. MSK offers precise radiation therapy that kills rectal cancer cells with fewer radiation side effects. This keeps the healthy tissue safe.
You may have radiation treatment for rectal cancer on its own. Or, you may have it before, during, or after surgery or chemotherapy. Rectal cancer radiation given along with chemotherapy is called chemoradiation.
To understand how rectal cancer radiation therapy fits into your treatment, this is a good place to start.
MSK Care Advisors are available 24 hours a day, 7 days a week to answer your questions.
How is radiation therapy used to treat rectal cancer?
Your doctor may recommend radiation therapy for rectal cancer that’s only in your rectum but cannot safely be removed with surgery. The pelvis has many narrow parts, making the area hard to do surgery on.
Radiation therapy works by using very precise, powerful, high-energy beams to kill cancer cells.
Radiation oncologists are cancer doctors with special training in using radiation to treat cancer. MSK’s radiation therapy experts deliver radiation to the tumor while keeping nearby healthy tissue safe. Radiation therapy aims to kill off rectal cancer cells with as few side effects as possible.
Rectal cancer may not respond to surgery or chemotherapy. If so, we use radiation therapy to relieve symptoms and improve your quality of life.
Types of radiation therapy
There are 2 basic kinds of radiation therapy, internal and external:
External radiation therapy is delivered from outside your body. This kind of therapy uses high-energy rays to harm cancer cells so they can no longer grow.
External beam radiation therapy (EBRT) uses a treatment machine called a linear accelerator. A linear accelerator aims beams of radiation right at the tumor.
The beams pass through your body and harm cancer cells in their path. You will not see or feel the radiation.
Most energy rays used for EBRT are photons (X-rays or gamma rays). Another type of EBRT is proton therapy, which uses proton rays.
EBRT is the most common type of radiation therapy for rectal cancer.
Internal radiation therapy is when we put something, such as radioactive seeds, inside your body very close to the tumor. This is called brachytherapy (BRAY-kee-THAYR-uh-pee).
Doctors at MSK are national experts in all methods of radiation therapy. They’ll recommend which is best for you, based on the cancer and your preferences.
MSK uses proton therapy, also called proton beam therapy, for only some cases of rectal cancer. It may be a treatment for younger people, or if you already had radiation to the pelvis.
This type of radiation therapy uses charged particles called protons to kill cancer cells. A device called a cyclotron sends tiny, high-energy beams of protons to the tumor.
With proton therapy, the beams do not go past the tumor. It can cause fewer side effects because healthy tissue near the tumor is more likely to be safe.
Intensity-modulated radiation therapy (IMRT) lets us change the radiation beams’ power during treatment. IMRT uses a special computer program. It lets us make a dose plan that can deliver high doses of radiation more precisely to the tumor area.
IMRT can have fewer side effects for some people because it’s so accurate.
You’ll have a CT scan before IMRT to make a 3D map of the tumor. Most treatment sessions take 10 to 30 minutes, and you’ll have them 5 days a week for a few weeks.
IMRT most often is used to treat tumors near the anus, or rectal cancer that came back after surgery. You also may have chemotherapy to make radiation work better.
Endorectal brachytherapy (BRAY-kee-THAYR-uh-pee) is internal radiation therapy.
It’s an option for some people who cannot have surgery and cancer came back in the rectum after external radiation therapy.
At the hospital, you’ll have anesthesia (medicine to make you sleep). You can go home the same day.
Brachytherapy puts radioactive material close to or inside the tumor. The radioactive material is sealed inside a thin tube. The radiation does not travel far from the radioactive material. The tumor gets a high radiation dose while nearby healthy tissue gets little or none.
Intraoperative radiation therapy (IORT) is a high dose of radiation given during rectal cancer surgery.
IORT is used with tumors that are hard to remove without harming nearby tissue. It’s often for rectal cancer that came back in the pelvis after surgery and radiation therapy. Some people have IORT because they cannot safely have more EBRT.
IORT delivers a single focused dose of radiation right to the area where the tumor was removed. This helps kills any cancer cells left behind. IORT uses radioactive seeds. The treatment area gets a high radiation dose while nearby healthy tissue gets little or none.
Chemotherapy with radiation (chemoradiotherapy)
Chemoradiation is when we use chemotherapy together with radiation. It’s a common treatment for rectal cancer.
Radiation can work very well, but chemotherapy helps the radiation work better. Chemotherapy also can treat very tiny cancer cells that may have spread outside the area where the cancer started.
Side effects of rectal cancer radiation therapy
What are the short-term side effects of rectal cancer radiation therapy?
Radiation treatments are very precise and cause little harm to healthy tissues. Radiation for rectal cancer does not cause hair loss. Many people report few lasting side effects.
In general, you can keep doing your daily activities or keep working through treatment.
Some people do have side effects during or shortly after rectal cancer radiation. They include:
- Skin irritation
- Diarrhea
- Rectal discomfort or pain
- Bloating or cramping feelings
- Fatigue (feeling very tired)
Our Integrative Medicine and Wellness Service offers acupuncture, meditation, massage therapy, yoga, and exercise. Integrative medicine is also called complementary, natural, or holistic treatments. Without using prescription drugs, integrative therapies can help improve and control side effects of cancer treatment.
What are the long-term side effects of rectal cancer radiation therapy?
Some side effects can start months or years after radiation treatment ends. These are called long-term or late effects. Serious (very bad) late effects of rectal cancer radiation are not common. They can include:
- Rectal bleeding
- Diarrhea
- Incontinence (leaking) stool (poop)
- Fractures, or arthritis in bones in the pelvis
- Sexual side effects, such as a dry vagina or erectile dysfunction (trouble getting hard)
How do we limit exposure to radiation during treatment?
MSK’s radiation experts do everything possible to lower the chances of harming your body. They use the most precise ways to deliver radiation to treat the rectal tumors and not nearby healthy tissue.
For safety, we can take images each day to see the bones or tumor and keep healthy tissue safe. These methods limit healthy tissue’s exposure to radiation.
Tools for predicting rectal cancer survival and cancer coming back
MSK’s online prediction tools (nomograms) predict rectal cancer 5-year survival rates and the chance of recurrence after rectal cancer treatment. Our clinical calculators can help your doctor and you make important decisions about treatment and your follow-up care.
One rectal cancer nomogram predicts whether you’ll have no signs of rectal cancer 5 years after your treatment. It also predicts the chance you’ll survive rectal cancer at least 5 years after treatment. This tool is for people who had chemotherapy, radiotherapy, and surgery for rectal cancer.
Another rectal cancer nomogram predicts the chance you’ll have no signs of rectal cancer 5 years after your treatment. It’s for people who had total neoadjuvant therapy, which combines chemotherapy and radiation therapy. You must also have had surgery or watch-and-wait active surveillance..
Learn more about our rectal cancer prediction tools.
MSK helps you live your best life after rectal cancer treatment. Our advanced practice providers have special training to make a follow-up care plan after radiation therapy. They’ll guide you to the right kind of support, such as rehabilitation and exercise, based on your needs.
Common questions
Before radiation therapy, you’ll have a treatment planning procedure called a simulation. It’s done so that:
- Your treatment site is mapped so the radiation is precise and targeted.
- You get the right radiation dose.
- Nearby tissue gets the least amount of radiation possible.
Your simulation takes about 1 hour. You’ll have a CT scan.
We’ll mark your skin with tiny tattoo dots about the size of a freckle. This tells us which area to treat. These tattoos are permanent (do not come off).
Some people may have a positron emission tomography-computed tomography (PET-CT) scan done during the simulation.
Your radiation oncologist will work with a team to plan your treatment. Together, they’ll plan the angles and shapes of your radiation beams. This information is carefully planned and checked. Your radiation treatments will take 5 to 30 visits, scheduled on weekdays 1 day after another.
Your radiation therapy team will tell you what to expect for your treatment schedules.
You must come in each day you’re scheduled for your treatment. Treatment may not work as well if you skip or miss appointments. If you need to change your schedule for any reason, talk with your radiation therapist.
Before your appointment, it’s helpful to write down questions to ask your radiologist who is an expert in rectal cancer. Here are some examples. Write down the answers during your appointment so you can review them later.
- How will radiation to my rectal area make me feel?
- What kind of radiation therapy will I get?
- How many radiation treatments will I get?
- What side effects should I expect during radiation therapy?
- Will these side effects go away after I finish radiation therapy?
- What kind of late side effects should I expect after radiation therapy?
- What kind of follow-up care will I need after radiation therapy ends?