People with rectal cancer often have radiation therapy along with chemotherapy to shrink their tumor before surgery. This makes the tumor easier to remove from the small space in and around the rectum, and it decreases the chance that the cancer will return.
If your cancer has spread to other parts of your body, radiation therapy may also be helpful for treating those specific spots.
External-beam radiation therapy (EBRT) aims high-energy X-rays or other types of radiation at your body to kill cancer cells. Three main types are used for rectal cancer: intensity-modulated radiation therapy, proton therapy and intraoperative radiation therapy.
Intensity-modulated radiation therapy (IMRT)
For rectal cancer, doctors most often use IMRT.
- IMRT uses a computer-controlled linear accelerator that moves around you to deliver X-ray radiation.
- It shapes the beams and aims them at the tumor from several angles.
- The intensity of the beams can be adjusted to lessen the dose that reaches sensitive normal tissue.
- You will most likely get chemotherapy at the same time (called chemoradiation) because chemo can make cancer more sensitive to radiation.
Learn more in our radiation oncology section.
Proton therapy is a unique form of EBRT that targets protons at tumors to kill cancer cells.
- Proton therapy may significantly limit radiation exposure to surrounding healthy tissue near the rectum, such as the bowel and bladder.
- This may reduce side effects from treatment and allow for a shorter course of treatment compared with X-ray radiation therapy.
- Proton therapy may be particularly useful if you have recurrent tumors and had radiation therapy to the same area in the past.
The SCCA Proton Therapy Center is the only proton facility in the Pacific Northwest. Learn more about proton therapy for rectal cancer.
Intraoperative radiation therapy (IORT)
Your SCCA team may recommend IORT if:
- You have locally advanced rectal cancer that is attached to normal structures (such as nerves or blood vessels) that cannot be removed.
- You have recurrent tumors.
IORT is a fast and effective form of radiation therapy that uses electron-beam radiation during surgery.
- Your surgeon moves normal structures out of the way to expose the area for this precise, high-dose treatment.
- It takes only a few minutes to deliver and uses only a fraction of the total radiation given over a traditional multi-week course of external-beam radiation.
University of Washington Medical Center (UWMC) is the only hospital in the WAMI region (Washington, Alaska, Montana and Idaho) to offer this treatment. Learn more about IORT.