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The first important thing to understand about colorectal cancer: you are not alone, as you will see in the highlighted facts below. Colorectal cancer is a “gastrointestinal” cancer which affects the tissues of the digestive tract including the colon and rectum. Today, options for treating colorectal cancer, including radiation therapy, continue to advance. Throughout your cancer journey—from screening and diagnosis to treatment and survivorship—your medical care team is with you every step of the way.

Colorectal cancer is the third most common cancer type worldwide.

Almost 2 million colorectal cancer cases were diagnosed across the globe in 2020.

When colorectal cancer is found early, it is highly treatable.

Colorectal cancer

Your treatment plan

There are a variety of treatment options for colorectal cancer. Your treatment plan will depend on several factors, including the location of the cancer, the stage of the disease, your age and general health, and whether the cancer is new or recurrent.

For colorectal cancer, many patients are treated with various combinations of surgery, chemotherapy, radiation therapy, targeted drug therapy, and immunotherapy.

The first line of treatment for most colorectal cancer patients involves surgery to remove the cancer. Your physicians will help you decide what kind of surgery, if any, is best for you.

Radiation therapy may be used if surgery is not an option. It may also be used before surgery to make removal of the cancer easier, or after surgery to decrease the chances of cancer recurrence. Radiation therapy may be combined with chemotherapy treatment.

Colorectal cancer

Radiation therapy treatment techniques

There are different types of radiation therapy techniques that may be useful for colorectal cancer treatment, including:

Colorectal cancer

Possible side effects

Side effects are cumulative, which means they can develop over several weeks or months as the body responds to radiation . You can ask your radiation oncologist what you might expect from your specific treatment. These are some common side effects of colorectal cancer radiation therapy:

  • Fatigue
  • Nausea
  • Skin irritation
  • Pain or burning while urinating
  • Rectal irritation including bloody stools, diarrhea and painful bowel movements

Colorectal cancer

Your EBRT treatment journey

When it comes to preparing for your colorectal cancer treatment, knowledge is power. That includes knowing what to expect during your treatment journey so you can move forward one informed and empowered step at a time. Here is a brief outline of what you can expect during external beam radiation treatment. The details of some steps may differ, depending on your particular case.

Step 1: Consultation

First, you'll meet with your radiation oncologist to discuss what type of radiation treatment options are recommended for your specific case, and make a decision together about your treatment.

Step 2: Simulation

As part of your treatment planning, the exact area of the tumor must first be determined. This is usually done using a CT scan, short for computed tomography, providing a detailed 3-D image of the treatment area using x-rays. Sometimes temporary skin marks or even tiny tattoos (about the size of a freckle) are made on your body to help the radiation therapist position you correctly each day for treatment.

Step 3: Treatment planning

After simulation is complete, your radiation oncologist will develop your personalized treatment plan, taking into account the location, type and stage of cancer you have, your medical history, lab tests, and other factors—all to determine your best course of treatment. Typical treatment with radiation therapy will require you to come for treatment five days a week.

Step 4: Positioning for treatment

On your treatment days, your radiation therapist will position you on the radiation machine’s treatment couch. The couch will be adjusted so the radiation laser targets the small mark that was put on your skin during your simulation, ensuring you are properly aligned for treatment.

Step 5: Start of treatment

The radiation is delivered by a machine called a linear accelerator, or linac. The linac will move around you to deliver the radiation. You won’t see, hear, feel or smell the beam. Treatment sessions usually take approximately 15 minutes. Your first treatment session may be a little longer.

Step 6: Post-treatment and follow-up care

Every patient is different, but most patients can continue daily activities during treatment, despite side effects such as fatigue. After your final treatment, your radiation oncologist will schedule periodic follow-up appointments to monitor your progress and the results of your treatment.

Colorectal cancer

Helpful resources for colorectal cancer

Questions to ask

Some important things you may want to find out from your doctor before undergoing treatment for colorectal cancer.