Is Rectal Cancer The Same as Colon Cancer?

Differences and Similarities Between Rectal and Colon Cancers

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Have you ever wondered, is rectal cancer the same as colon cancer?

In theory, yes. Colon and rectal cancers involve the large intestine and are commonly referred to as colorectal cancer. However, when it comes to treatment options, rectal cancers are approached with the goal of saving bowel function if possible.

What is the Rectum?

The last 10-15 inches of your large intestine are called the rectum. This hollow organ is basically a housing for stool that is waiting to be evacuated from the body via the anal sphincter (anus).

Rectal tumors can spread locally -- meaning they can invade the tissues of the anus, pelvis and even neighboring organs such as the bladder, pelvic bones or the reproductive organs.

Symptoms of Rectal Cancer

The signs and symptoms of rectal cancer are similar to those of distal colon cancers. Rectal cancers usually begin as a polyp in the rectum. The symptoms are dependent on the size of the growing mass. A large mass in the rectum can make you uncomfortable by creating:

  • Feelings of fullness in the rectum
  • Constant urge to have a bowel movement
  • Pressure within the rectum
  • A blockage, which makes bowel movements thin or ribbon-like as they pass the tumor
  • Blood in the stool
  • Feeling that your bowels have not completely evacuated after a bowel movement
  • A painful spasm or cramping sensation in the anus

Finding the Cancer

During a digital rectal examination (DRE), your doctor uses his or her gloved finger to feel for masses in the rectum.

However, this is only a part of a complete physical exam; it is not an approved screening test for colorectal cancer, according to the National Cancer Institute. Not all lumps and masses felt are cancer -- and some cancerous masses may be missed with a rectal exam. If your doctor has reason to suspect rectal cancer, he or she can order tests to get a better look inside, including:

Treating Rectal Cancers

Treatment is focused on restoring or maintaining bowel function if possible. Surgery, radiation and chemotherapy are used to treat rectal cancers, with surgery the foremost option. Surgical removal of your rectum is called a proctectomy. Depending on the stage and grade of your rectal cancer, the doctor may be able to simply remove small, non-invasive tumors through a colonoscopy or sigmoidoscopy, or you may need a more invasive surgery. Surgeries to remove rectal cancers may include:

  • Transanal excision of the cancer (through the anus)
  • Anterior resection
  • Abdominoperineal resection
  • Pelvic exenteration (removing adjacent organs due to metastasis)
  • Extended and radical resections (usually resulting in a permanent colostomy)

Transanal Excision

The transanal excision is a surgical approach used to remove rectal tumors that have not invaded nearby tissues. The borders of the tumor are well-defined and the surgeon can cut it out through the anus.

Resections

A resection is a fancy way to say opening and cutting the tumor out. There are many different types of resection surgeries for rectal cancer, which are named by the approach taken to get to the rectum. The surgeon may need to cut out the entire rectum as well as the final portion of the colon. If the anal sphincter must be removed as well, the surgeon will create an artificial opening in your abdomen, called a stoma, where stool contents can be expelled. This stoma is called a colostomy and is nonreversible if your anus has been removed.

Pelvic exenteration is the term given to removal of affected pelvic organs during surgery. If the bladder, colon or reproductive organs are diseased, they can be removed during the abdominal resection.

Surgical Complications

Like any other surgery, surgery for rectal cancer involves a certain amount of risk, although bowel surgery recovery is usually pretty straightforward. Complications may include bleeding, infection, impotence in men, or problems with the stoma or intestinal connections (the anastamosis).

Other Forms of Treatment

Radiation and chemotherapy may be used in conjunction with surgery to cure advanced rectal cancers. Both forms of treatment may be used prior to surgery to shrink very large rectal tumors for removal.

References:

American Cancer Society. (2006). American Cancer Society's Complete Guide to Colorectal Cancer. Clifton Fields, NE: American Cancer Society.

American Cancer Society. (n.d.). What are the Survival Rates for Colorectal Cancer by Stage? Accessed July 15, 2012.

National Cancer Institute. (n.d.). Colorectal Cancer Screening. Accessed July 15, 2012.

The Society for Surgery of the Alimentary Tract. (n.d.). Surgical Treatment of Cancer of the Colon or Rectum. Accessed July 12, 2012.

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