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What is radiation?

You might hear you’re getting radiation treatment. But what is it, exactly?

Radiation oncologists use beams of high energy to alter and damage the DNA in cancer cells, ultimately killing them. These beams come from a highly specialized machine, and are aimed directly at your tumor. You will not see or feel the beams going into your body during treatment.

Radiation can also affect healthy cells, although side effects may take a few days to set in. Radiation therapy takes time to work, and will continue to work in the body for several weeks after treatment has finished.

How is radiation used to treat colorectal cancer?

Radiation treatment can be used:

  • Before, after, or during surgery to kill any cancer cells left over and prevent the tumor from coming back
  • As a palliative measure, if a patient is unable to undergo surgery or if the tumor is causing pain or a blockage
  • To treat metastases in the lungs, brain, bones, liver, or other areas
  • As a local treatment done concurrently with systemic treatment — like chemotherapy or immunotherapy

Radiation is more commonly used to treat primary rectal cancer than colon cancer. If you have been diagnosed with rectal cancer, it’s more likely that radiation will be part of your treatment plan. This is because most of the rectum does not have a protective peritoneal covering that encircles the colon. This makes it more likely for a rectal tumor to break through and spread locally in the pelvic cavity (the space between your pelvic bones). Tumors here are difficult to treat with surgery.

If surgery is a part of your treatment plan, you will likely have radiation first to help kill cancer cells, shrink the tumor, and make it easier for your surgeon to get all of the cancer while sparing the healthy parts of your rectum. 

Want to learn more about the differences between colon and rectal cancer? 

Check out this article by the University of Michigan. 

Find out more about radiation therapy here:

Check out this DocTalk with Dr. Sanford to learn about radiation for CRC:

How will radiation fit into my treatment plan?

If radiation is part of your treatment plan, your healthcare team will first take into consideration your entire treatment history and any future treatments that are planned. 

This is because there are limits on the recommended amount of radiation you can receive over a lifetime. It’s also difficult to re-treat an area that has already been treated with radiation. This means that if you have any local recurrances, your treatment options may be more limited.

If you have any concerns about how radiation may affect your future treatment plan, it’s important to speak up and ask your care team.

Can radiation be combined with other treatments?

Yep, radiation can be combined with other treatments, such as chemotherapy or immunotherapy. Oral chemo pills (like capecitabine/Xeloda) are often given alongside long-course radiation.

Want to learn more about radiation?

Join Rectalburgh, one of our COLONTOWN Facebook groups. Here, we discuss all things related to rectal cancer, including long and short course pelvic radiation.

Want to join? Fill out the registration form here.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: April 28, 2022