Differences Between Colorectal Cancer and Colon Cancer

Similarities and Differences Between Colon Cancer and Rectal Cancer

Colon. Credit: ericsphotography

 

Are colorectal cancer and colon cancer the same thing or are there any differences between the two?

Colorectal Cancer vs Colon Cancer

The answer to this question needs some explanation because it is both yes and no.  Often colorectal and colon cancer are used to describe identical things.  The term colorectal cancer includes rectal cancer, but many articles and research studies use the terms interchangeably.

  The term colon cancer may be made in a way in which it includes rectal cancer, and the term colorectal cancer may be used to describe primarily colon cancer; the information may not apply as well to rectal cancer.

Anatomy of Colon/Colorectal Cancer

The colon and rectum are both a part of the large intestine, the final destination of the gastrointestinal tract.  The colon is approximately 5 feet long and is separated into the proximal colon - the first portion which is attached to the small intestine, and the distal colon - the second portion which is attached to the rectum.  The rectum (which is also part of the colon) is the last 6 to 12 inches of the colon which reaches to the anus.

Differences (and Similarities) Between Colon and Rectal Cancer

The distinction as noted above is not between colorectal cancer and colon cancer, but rather between colon cancer and rectal cancer.  There are many similarities between the two, but some very important differences as well.

  As will be discussed, the biggest differences are between the treatment approach and the prognosis.

Incidence and Causes - Colon cancer and rectal cancer are more alike than different when it comes to possible causes and risk factors, and how common they are.  Colon cancer is pretty much equal between the sexes, whereas rectal cancer is somewhat more common in men than women.

  An association between red meat and cancer is present for both, but much stronger for rectal cancer than for colon cancer.

Invasion of Nearby Tissues - Colon cancer, being in the abdomen, has much more "room" around it, whereas rectal cancer occurs in a much tighter spot.  Rectal cancer therefore has a greater chance of spreading early to nearby tissues such as the male and female reproductive organs and the bladder.

Difficulty of surgery/surgical approaches - Colon cancer is a much easier surgery in general than rectal surgery.  With rectal surgery it is more difficult to get access to the tumor, and dissecting the tumor out from this area of many structures can be more challenging.

Treatments - Treatments for the two cancers differ somewhat.  Surgery for colon cancer may be recommended at any stage of the disease, and surgery alone without chemotherapy or radiation therapy is usually the treatment for stage 1 and 2 disease.  With rectal cancer, surgery may be done for stage 1 to 3 disease, but chemotherapy may be recommended as well, even for stage 1 disease.

  Radiation therapy is often recommended for rectal cancer, but infrequently for colon cancer.

Need for a permanent colostomy - People who have surgery for rectal cancer have a much greater likelihood of needing a permanent colostomy than do people with colon cancer, in which a colostomy is the exception rather than the rule.  The main problem is the presence of the anal sphincter.  With colon cancer, even if a colostomy is done temporarily, it is often possible to go back in and reattach the colon later on (anastomosis.)  With rectal cancer, if it is necessary to remove the anal sphincter, this cannot be recreated with surgery and the patient will need a permanent colostomy.

Need for radiation therapy - Radiation is not commonly used for colon cancer, but is needed often for rectal cancer.  It may be used in stage 2 and 3 is often used before and after surgery.

Chemotherapy timing - Chemotherapy for colon cancer is often used as an adjunct to surgery in stage 3 patients (and sometimes stage 2) and for stage 4 disease.  With rectal cancer, chemotherapy may even be used with stage 1 cancer and is commonly used in stages 2 through 4.

Prognosis - The prognosis for rectal cancer is poorer than that of colon cancer.  Rectal cancer is more difficult to cure, and the rate of recurrence is between 15 and 45% of patients.

Sources:

American Cancer Society. What is colorectal cancer? Updated 12/31/14. http://www.cancer.org/cancer/colonandrectumcancer/overviewguide/colorectal-cancer-overview-what-is-colorectal-cancer

National Cancer Institute. Colon Cancer Treatment (PDQ_ - for health professionals. Updated 01/-7/16. http://www.cancer.gov/types/colorectal/hp/colon-treatment-pdq

National Cancer Institute. Rectal Cancer Treatment (PDQ) – for health professionals. Updated 01/28/15. http://www.cancer.gov/types/colorectal/hp/rectal-treatment-pdq

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