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Colorectal cancer and radiation

Overview

Colorectal cancer is the term for cancers found in the colon or the rectum, which make up the large intestine. It may also be referred to as bowel cancer. Colorectal cancer often begins as a growth called a polyp inside the colon or rectum. Colon cancer and rectal cancer are grouped together because they share many characteristics, symptoms, and treatments. Colorectal cancer is one of the most common cancers and affects both men and women.

More information

You can find additional information on colorectal cancer on our Cancer Resources page.

Information on this page was resourced from:

American Cancer Society

National Cancer Institute

Cancer Treatment Centers of America

About colorectal cancer

Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women. Thanks to improvements in prevention, early detection, and treatment, more than a million people in the US count themselves as survivors of colon or rectum cancer (also called colorectal cancer).

At MRO, we understand the uncertainty that comes with a colorectal cancer diagnosis. Our oncologists and supportive care teams are committed to helping you understand the complexities of the disease and how radiation treatment may help with your cancer. Our MRO oncologists offer a level of expertise that comes from working exclusively with radiation cancer treatments and patients every day. 

Colorectal cancer is the term for cancers found in the colon or the rectum, which make up the large intestine. It may also be referred to as bowel cancer. Colorectal cancer often begins as a growth called a polyp inside the colon or rectum. Colon cancer and rectal cancer are grouped together because they share many characteristics, symptoms, and treatments.

The treatments and side effects of this disease may impact your quality of life. That’s why it’s important to turn to doctors with expertise in colorectal cancer—experts who will work to help you understand the disease and to see if radiation therapy is the right choice for you.

Types of colorectal cancer

Almost all cancers found in the colon and the rectum are adenocarcinomas. Less common types of colorectal cancer include primary colorectal lymphomas, gastrointestinal stromal tumors, leiomyosarcomas, carcinoid tumors, and melanomas. Adenocarcinomas make up 95% of all colorectal cancer cases. Polyps are often removed during a routine colonoscopy before they may develop into cancer.

Of the rarer types of colorectal cancer, gastrointestinal carcinoid tumors grow slowly, form in the neuroendocrine cell and make up 1% of all colorectal cancers, whereas primary colorectal lymphomas develop in the lymphatic system and account for 0.5% of colorectal cancers.

Radiation treatment options

Your oncologist may offer radiation therapy as a colorectal cancer treatment option for a number of reasons, including: 

  • Radiation therapy delivered before surgery may help shrink tumors so they are easier to remove.
  • Radiation therapy given after surgery may help kill cancer cells that have been left behind.
  • The treatment may be an option for patients who are unable to undergo surgery.
  • Radiation therapy may be used as palliative treatment, to help shrink tumors that may be causing a blockage in the colon or intestines.
  • Radiation therapy may be given in conjunction with chemotherapy.

External Beam Radiation Therapy (EBRT)