Radiation Therapy

Radiation therapy uses high-energy X-rays or other types of radiation to kill cancer cells.

People with rectal cancer often have radiation therapy before surgery (neoadjuvant radiation therapy) to shrink their tumor. 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 the cancer has spread (metastasized) to other parts of the body, radiation therapy may also be helpful for treating those specific spots.

Patients of Seattle Cancer Care Alliance (SCCA) may receive radiation therapy at these locations:

• SCCA Radiation Oncology at the SCCA clinic near Lake Union
• SCCA Radiation Oncology at Northwest Hospital & Medical Center
• University of Washington Medical Center

Intensity-Modulated Radiation Therapy (IMRT)

External-beam radiation therapy uses a machine called a linear accelerator to send beams of radiation toward the cancer. For rectal cancer, doctors most often use a type called intensity-modulated radiation therapy (IMRT). IMRT uses precise imaging and computers to map your tumor. This helps your radiation oncologist accurately plan your radiation therapy and target the beams to your tumor.

Radiation therapy treatments are given Monday through Friday for about five weeks. If your treatment involves radiation therapy, your radiation oncologist will determine the dosage and schedule for your treatments, will help you manage any side effects, and will work closely with other members of your care team. Learn more in the section on radiation oncology.

Chemotherapy and Radiation Together

If you’re having radiation therapy, you will most likely get chemotherapy at the same time. This combination is called chemoradiation. Chemotherapy drugs can make cancer cells more sensitive to radiation.

Side Effects of Radiation Therapy

Radiation therapy can cause side effects, which may depend on exactly how and where the radiation is given. Fatigue is a common side effect. Radiation therapy to the pelvic area may also cause gastrointestinal problems (like upset stomach and diarrhea), sexual problems, and infertility. Your team at SCCA will talk with you about the specific side effects you might experience, and we will help you prevent, reduce, or manage these effects as best as possible. You can find general information in the symptom management section.