Radiation Therapy for Rectal Cancer

In patients with rectal cancer, radiation can prevent the tumor from recurring after it has been removed with surgery. Other times, radiation can even eliminate rectal tumors on its own.

To receive radiation therapy, patients must come to a treatment center regularly over a sometimes-lengthy period of time. Radiation oncologists at Siteman are national leaders at using shorter durations of radiation to achieve the same positive results. As a result, Siteman patients are often able to complete their treatments more quickly than patients at other cancer centers.

How does radiation therapy treat rectal cancer?

The goal of radiation therapy is to kill cancer cells by causing irreparable damage to their DNA.  At Siteman, most patients with rectal cancer are treated with external beam radiation, or radiation that’s transmitted by a machine.

Some variations on external beam radiation therapy include:

Intensity-modulated radiation therapy (IMRT)

Intensity-modulated radiation therapy delivers radiation beams that are tailored to the three-dimensional shape of the tumor. Radiation technicians and specialists are able to do this by using large-bore CT simulation to get a 3D visual of the tumor and carefully controlling the strength of each beam during the treatment process itself.

Because IMRT is shaped to the tumor so precisely, it has minimal impact on the tissues and organs surrounding it. This helps protect the patient from side effects or other issues that could arise later on.

MR-guided adaptive radiation therapy

MR-guided adaptive radiation therapy unites MRI visualization to the delivery of radiation for highly-targeted treatment. The MRI allows radiation oncologists to watch how the radiation is impacting the tumor during the treatment itself, enabling them to make adjustments on the spot to radiate the tumor better while protecting surrounding organs and structures.

Siteman Cancer Center was the first institution in the world to use MR-guided adaptive radiation therapy to treat a patient. The technology was developed by physicians and researchers based at Washington University and Siteman, many of whom are still on staff today.

Colorectal cancer patients may receive MR-guided adaptive radiation therapy if they require an enhanced dose to a tiny area, such as the lymph nodes. Siteman radiation oncologists are exploring additional applications of this therapy in clinical trials. Talk to your care team about whether you might be eligible for a trial.

What is it like to receive radiation therapy?

Radiation therapy is just like getting a diagnostic scan such as an X-ray. It’s a painless procedure that typically takes less than half an hour.

During radiation therapy, you will lie still on a table while a scanner quietly moves around your body and takes CT images. The technicians will align these new images with previous scans to pinpoint the location of the tumor.

After this brief planning session, radiation will be delivered to your tumor. You won’t feel anything, and the process only takes a few minutes. To help you feel more comfortable, the staff will play the music of your choice in the treatment room.

What are some of the side effects of radiation therapy for rectal cancer?

Following radiation therapy for rectal cancer, some patients may notice:

  • Fatigue
  • Diarrhea
  • Sexual problems

Speak to your care team about any side effects you may be experiencing. There are steps they can take to help you feel better.