Colon and Rectal Cancers: What Are the Differences?

You hear the term colorectal cancer a lot, which is a combination of the words colon and rectal. But they are actually two different types of cancer that occur in the same general area of the body. While they are different there are some similarities in how they’re treated. And, because of where the cancer is located, there are also some differences. Let’s look at what they are.

What’s the Difference Between Colon Cancer and Rectal Cancer?

The colon and rectum are both parts of the large intestine, which is the lowest part of the digestive system. The colon is the last five feet of the large intestine, and its primary purpose is to absorb water from the stool. This part of the large intestine is in a relatively open area below the bottom of the rib cage and above the pelvis. For many people, there aren’t a lot of early signs of colon cancer because it has space to grow before causing noticeable problems.

The rectum is the last five inches of the colon, which is where stool is stored until it’s eliminated with a bowel movement. The rectum is in a crowded area, with many organs nearby. These include the vagina and uterus for women and the prostate gland for men. The bladder is also close to the rectum for both men and women. Because of this, rectal cancer is a little more likely to impact bodily functions such as bowel movements, urination and sex, depending on where it’s located, how large it is and whether it has spread.

There is one other difference between the colon and rectum that is important to note. The colon has a protective outer layer called the serosa, which makes it more difficult for cancer cells to break through and spread to other parts of the body. The rectum doesn’t have the serosa. This means it is somewhat easier for the cells to spread to those other nearby organs at a faster rate, and could even contribute to the higher recurrence rate that rectal cancer patients experience.

Symptoms of Colon and Rectal Cancers

The early symptoms of colon and rectal cancer are often similar since the rectum is part of the colon. These symptoms include the following:

• Black or red stools
• Rectal bleeding
• Constipation that doesn’t go away
• Diarrhea that doesn’t go away
• Fatigue for no apparent reason
• Stomach pain that doesn't pass after a bowel movement
• Feeling that you still need to have a bowel movement after you’ve finished one
• Skinny/thin feces

Screening for Colorectal Cancer

Doctors use the same screening tests for both colon and rectal cancers. Some doctors start with a stool test that is done at home and sent in for results to see if there is any indication of cancer cells. If there is, further testing will have to be done to see exactly where the cancer cells started.

A colonoscopy is highly effective at detecting early cancer anywhere in the large intestine. This procedure consists of a doctor using a long, flexible tube to see the inside the colon and rectum. The doctor will also take a small sample, or biopsy, of any areas that look like they could be cancer. Small growths known as polyps are common in the colon, but aren’t cancer. However, they may still need to be removed, as they could cause problems later. Learn more about the guidelines for colorectal cancer screenings.

Early detection of colon or rectal cancer provides the best chance of successful treatment, regardless of its type. The removal of suspicious growths before they cause symptoms prevents 90 percent of colon and rectal cancers. Working with an experienced team is also critical for a positive outcome.

How is Colon Cancer Treated Differently From Rectal Cancer?

The treatments for colon and rectal cancer are generally the same with some differences.

Surgery is Used for Both Colon and Rectal Cancers

Surgery is the most common treatment for both colon and rectal cancer, although each type has specific techniques and risks. Patients may still need chemotherapy and/or radiation therapy to kill remaining cancer cells, even when surgery is the primary treatment.

Colon Cancer Surgery

A partial colectomy is usually the first surgical treatment for colon cancer, which involves removing only a section of the colon. Surgeons can typically reconnect the separated portions of the colon, allowing you to have normal bowel movements. In some cases where it can’t be reconnected right away, you may need a colostomy.

A colostomy is a procedure that involves creating a hole, or ostomy, in your abdomen and attaching the end of your colon to the ostomy. A bag connected to the outside of the ostomy then collects the bowel movements. This is not always a permanent condition. For some patients, after some healing of the colon, the two parts can be reconnected and the ostomy closed.

Rectal Cancer Surgery

Surgery to remove rectal cancer is a delicate procedure to help protect the nearby organs, and to try to keep the rectum intact. Your surgeon will try to cut out tissue affected by the cancer without removing your anal sphincter, which opens and closes the anus during bowel movements. In cases where the anal sphincter can't be saved, you'll need a colostomy. The National Cancer Institute reports that about one person in eight with rectal cancer requires this procedure. For some with rectal cancer this may be a more permanent solution than it is for colon cancer patients but your surgeon will tell you more about what was done and what you can expect after surgery.

Chemotherapy and Radiation Therapy for Colorectal Cancers

Chemotherapy is typically used in cases where the cancer has spread to the lymph nodes and/or other parts of the body. It may also be used before surgery to shrink the tumor, making the surgery easier. It can also be used after the surgery to treat any remaining cancer cells.

Radiation therapy for colon cancer is not commonly used but it is used more often for rectal cancers. Rectal cancer can use external or internal (high dose rate) radiation therapy depending on where it’s located.

Recurrence of Colon Cancer Versus Rectal Cancer

Colon cancer has a 2% chance of coming back at the same location, whereas rectal cancer has about a 20% recurrence rate. This difference in risk is particularly dangerous due to the important organs located close to the rectum.

What To Do If You Receive a Colon or Rectal Cancer Diagnosis

The experts at Cancer Care Centers of Brevard will help you through every step of the treatment process, including surgery and any other treatments that may be needed to help reduce the likelihood of colon or rectal cancer returning. We are also available for second opinions for colorectal cancer diagnoses. Contact our cancer centers located in Melbourne, Florida, and throughout Brevard County, Florida, for an appointment.

Categories: Colorectal Cancer