Radiation Therapy for Rectal Cancer

In patients with rectal cancer, radiation can prevent the tumor from recurring after surgery to remove it. 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. Washington University radiation oncologists at Siteman are national leaders at using shorter durations of radiation to achieve the same positive results. As a result, our patients are often able to complete their treatments more quickly than patients at other cancer centers.

Types of radiation therapy for 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)

This therapy involves radiation beams that are tailored to the 3D shape of the tumor. Our specialists use advanced technology to get a 3D visual of the tumor before delivering radiation. The strength of each radiation beam is controlled and the beam shape changes throughout treatment to conform to the tumor.

Will the radiation beams damage other parts of my body?

Because IMRT is shaped to the tumor so precisely, it has minimal impact on the tissues and organs surrounding it. This helps protect you from side effects or other potential issues down the road.

MR-guided adaptive radiation therapy

This therapy uses MRI visualization to deliver radiation for highly-targeted treatment. The MRI allows radiation oncologists to see how the radiation is impacting the tumor during the treatment, enabling them to make adjustments on the spot to radiate the tumor better while protecting surrounding 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 Washington University physicians and researchers at Siteman, many of whom are still on staff today.

When is MR-guided adaptive radiation therapy used?

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.

Receiving radiation therapy for rectal cancer

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. First, 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.

Does radiation hurt at all?

No! You won’t feel anything while receiving radiation, 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.

Will this therapy make me radioactive?

No, radiation therapy doesn’t cause you to become radioactive. The radiation is produced by our machine and isn’t active after treatment.

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

Following radiation therapy, some patients may experience:

  • Fatigue
  • Diarrhea or constipation
  • Skin problems
  • Hair loss
  • Loss of appetite
  • Fertility issues
  • Decreased libido or ability to enjoy sex
  • Low blood counts
  • Difficulty controlling bladder
  • Nausea and vomiting

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