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Colorectal and anal 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 or 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.

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About colorectal and anal 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).

Anal cancer is less common than colorectal cancer, but radiotherapy also plays a prominent role in treating and potentially curing anal cancer, often without a need for surgery.

At Minneapolis Radiation Oncology, we understand the uncertainty that comes with a colorectal or anal 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 radiation 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.

Anal cancer forms within the anal canal, just below the rectum. These cancers are typically of a different type than colorectal cancers, and are often treated differently (frequently without surgery); the radiotherapy treatment experience with anal cancer is similar to treatment of rectal cancer.

The treatments and side effects of these diseases may impact your quality of life. That’s why it’s important to turn to doctors with expertise in colorectal and anal cancers—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 and anal 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. Anal cancers are most commonly squamous cell carcinomas.

Radiation treatment options

Your oncologist may offer radiation therapy as an option for colorectal and anal cancer 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.
  • Radiation therapy may be an option for patients who are unable to undergo surgery, and in the case of anal cancer, radiotherapy is typically used as the primary treatment and patients may avoid surgery altogether.
  • 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 is often given in conjunction with chemotherapy for these diseases.

External Beam Radiation Therapy (EBRT)