When is Radiation Therapy Right for Me? Radiation therapy treats cancer by using high doses of radiation to kill cancer cells and shrink tumors. These high-energy rays are targeted toward the location of tumors in an effort to localize its effects. Though radiation is rarely used to treat colorectal cancer by itself, it is sometimes used simultaneously with chemotherapy. When radiation and chemotherapy are used in conjunction with each other, this is typically called chemoradiation or chemoradiotherapy. Radiation works by killing cancer cells by damaging their DNA, rendering them unable to continue dividing indefinitely. Once these damaged cancer cells die, the immune system can then break down the cells. When radiation is used in the treatment of colorectal cancer, it is typically used in conjunction with other treatment methods. When used with surgery, radiation therapy is typically used to shrink tumors to make them easier to remove, or to kill lingering cancer cells during or after surgery. Radiation is used alongside chemotherapy when a patient isn’t healthy enough for surgery, to treat cancer that has spread to other areas of the body, or palliatively, to ease symptoms of advanced stage cancer. Radiation Therapy for Colon Cancer Radiation therapy is not often used to treat colon cancer unless it is in the treatment of tumors that have grown next to or into other organs, to improve your quality of life, or to improve outcomes of surgery. Uses of radiation therapy to treat colon cancer include: Shrink tumors before surgery to make it easier to removeIntraoperative Radiation Therapy (IORT): Kill lingering cancer cells during surgeryKill lingering cancer cells after surgeryTreat a person who is not healthy enough for surgery, along with chemoTreat cancer that has metastasized to other areas of the bodyImprove the quality of life of patients with advanced stage cancer causing intestinal blockages, bleeding, or pain Radiation Therapy for Rectal Cancer Radiation therapy is more often used to treat rectal cancer in comparison to colon cancer, and it is used in similar ways – to treat tumors that have grown next to or into other organs, to improve your quality of life, or to improve outcomes of surgery. Uses of radiation therapy to treat rectal cancer include: Shrink tumors before surgery to make it easier to remove, especially if tumors are located in an area that is difficult to operateIntraoperative Radiation Therapy (IORT): Kill lingering cancer cells during surgeryKill lingering cancer cells after surgeryTreat a person who is not healthy enough for surgery, along with chemoTreat cancer that has metastasized to other areas of the bodyTo treat recurring tumors in the pelvis after radiation has been usedImprove the quality of life of patients with advanced stage cancer causing intestinal blockages, bleeding, or pain Learn more about radiation treatment for colon and rectal cancer in this CRC Webinar with Dr. Michael Bassetti from the UW School of Medicine and Public Health. We review why radiation therapy is used, how to prepare for treatment, how to manage side effects and more. Radiation Treatment webinar resources Advantages & Disadvantages of Radiation Therapy Advantages Decreases the chance of tumor recurrence in the pelvis or near the rectum and adjacent lymph nodes by 50%Decreases the chance of an operation causing permanent colostomyLess toxicity from chemoradiation if done prior to surgeryEffective, non-invasive, and well-tolerated for treating metastatic colorectal cancer Disadvantages Can cause new mutations to be created or new antigens to be expressedDying tumor cells release antigens and pro-inflammatory cytokinesRemoves immunosuppressive immune cellsInconvenience (e.g. in some cases radiation must be delivered daily)Can cause poor wound healing if surgery is performed after radiation therapy Types of Radiation Therapy The two main types of radiation therapy are defined by the method that radiation is delivered – externally or internally. External-beam radiation therapy is delivered by a machine aimed at the location of your tumor. Internal radiation therapy is delivered by a radiation source that is put inside the body in solid or liquid form. External-beam Radiation Therapy (EBRT) Machine emits radiation targeted at the location of a tumorLocal treatment: Only treats the area the radiation is delivered toTreatments given over the course of a few days to several weeks Internal Radiation Therapy Endocavitary Radiation Therapy Solid source of radiation are placed in the body in or near a tumorIn treating rectal cancer, a small balloon-like device is placed in the rectum to deliver radiation for a few minutesLocal treatmentTreatments typically given 4 times or less, with 2 weeks between each treatment Interstitial Brachytherapy Solid source of radiation are placed in the body in or near a tumorIn treating rectal cancer, tube is placed into the rectum and into the tumor to deliver radiation pellets for a few minutesLocal treatmentTreatments given a few times a week for several weeks, or can be a one-time procedure What to Expect from Radiation Therapy Your ability to carry on normal activities depends on the type of radiation therapy being administered and its frequency. Depending on the schedule of your radiation therapy, you may be required to stay at the hospital. Some patients may be able to perform normal daily activities, like working full-time or part-time, without much interruption, while others may be too fatigued. Side effects from radiation therapy typically go away after treatment in a few weeks or a few months. Over the course of your lifetime, there is a limit to the amount of radiation you can be exposed to. If you have had radiation therapy in the past, you may not be eligible to receive radiation to the same area of your body if you’ve reached your safe lifetime dose of radiation. However, if you have already reached your lifetime limit in one are of your body, you may be eligible to receive radiation therapy again targeted toward another area. Radiation Therapy Side Effects Radiation only affects the area of the body where it is administered (except in the case of systemic radiation therapy). Thus, radiation therapy for colorectal cancer should not cause hair loss, unless radiation is administered to the scalp. However, when given locally, radiation can also damage or kill nearby healthy cells that can cause negative side effects. Most side effects disappear after treatment Skin irritation at the site of radiation exposure (redness, blistering, or peeling)NauseaFatigueHindered wound healing if administered before surgeryRectal irritation (diarrhea, painful bowel movements, or blood in the stool)Bowel incontinenceBladder irritation (frequent urination, burning or pain, blood in the urine)Sexual problems (such as erectile dysfunction or vaginal irritation)Changes in menstruationInfertilityScarring or fibrosis that cause tissues to stick together More Treatment Resources Radiation therapy is only used to treat colon and rectal tumors under certain circumstances, and usually used in conjunction with other colorectal cancer treatments. Find out more about colorectal cancer chemotherapy and colorectal cancer surgery.