Colorectal cancer sounds like it’s one cancer. But if you consider the anatomy of the colon and rectum, it’s actually two. Rectal cancer vs. colon cancer: What’s the difference? 

Some people prefer to say they have colon cancer. Some will say they have colorectal cancer. Others say they have rectal cancer. 

No wonder people are confused. 

If you search “colorectal cancer” on the National Cancer Institute’s (NCI) website, it will yield more than 17,500 results. If you search “colon cancer,” you get about 15,550 results. Try searching “rectal cancer,” you will receive about 14,100 results. Finally, if you search “colon cancer and rectal cancer,” you receive 14,000 results. 

Why the discrepancy? What gives?

Colon Cancer vs. Rectal Cancer Broken Down

It’s called “colorectal cancer” because it is cancer that starts in the colon or the rectum, both of which make up the large intestine. But broken down, it’s colon cancer vs. rectal cancer because:

Colon cancer is cancer that begins in any part of the colon (ascending, transverse, descending, or sigmoid).

Rectal cancer is cancer that begins in the rectum, which is downstream from the colon.

Colorectal cancer is when a tumor is found at the junction of the sigmoid colon and rectum: Then it may be classified as “colorectal cancer.” This term is also used to describe both colon and rectal cancers.

So while we’re talking about colon cancer versus rectal cancer, should anal cancer be included in this discussion? No. Anal cancer is not the same as colorectal cancer.

When it comes down to diagnosing colorectal cancer, literally inches can make the difference between colon cancer and rectal cancer. It’s not uncommon for doctors to initially confuse colon cancer with rectal cancer or vice versa. 

Sometimes upon first visual examination, the tumor may appear to be in the colon, but subsequent scans and exams may pinpoint the origin of the tumor’s growth to the rectum or vice versa.

Is Colon Cancer and Rectal Cancer the Same?

While there are similarities between rectal cancer vs. colon cancer, they are not the same. Both colon and rectal cancers can develop from colon polyps, which can turn into tumors. Not all polyps turn into cancer. Adenocarcinoma is the most common type of colon and rectal cancers. Here are the similarities between colon cancer and rectal cancer:

• Both health history and other risk factors increase your chances of getting colon and rectal cancers.
• Blood in the stool or a change in bowel habits are symptoms of both colon and rectal cancers.
• Screenings that examine both the colon and rectum are used to diagnose colon and rectal cancers.
• Certain factors affect prognosis and treatment options for both colon and rectal cancers. 
• Recurrence is possible for both colon and rectal cancers.
• Newer types of treatment options are being tested in clinical trials for both colon cancer and rectal cancers.
• Genetic syndromes, like Lynch syndrome for example, can lead to both colon and rectal cancers.

Difference Between Colon Cancer and Rectal Cancer

Despite both the colon and rectum being housed in the large intestine, they are two different body parts with separate body functions. The colon absorbs water from stool and delivers stool to the rectum. 

However, the rectum serves as a holding area for stool, so we can control our bowel movements.

The colon is the main part of the large intestine and measures about 5 feet long. The rectum and anal canal make up the last part of the large intestine and are about 6-to-8 inches long. 

So, the difference between colon and rectal cancer is:

• Colon cancer occurs when cancer cells are formed in the tissue of the colon.
• Rectal cancer occurs when cancer cells are formed in the tissue of the rectum.

Surgery and Treatments for Colon and Rectal Cancers

Surgery, chemotherapy, radiation, immunotherapy, and targeted therapy are all treatment options for people with colon or rectal cancers.

Colon Cancer

Surgery

If you’ve been diagnosed with colon cancer, your first step will likely be surgery to remove the cancerous polyps and/or tumor. According to NCCN Guidelines for Patients® Colon Cancer 2022, “Surgery is the preferred and most effective treatment for colon cancer.” 

Your cancer stage will guide which type of surgery you need. Early-stage cancers (stage 0 and I) can be removed with less-invasive steps while later-stage cancers (II, III and IV) may require a more invasive surgery.

Surgery will remove the section of colon that contains the cancerous polyps, tumor, and surrounding tissue with its blood vessels and lymph nodes.

Chemotherapy

For stage II colon cancer patients, surgery to remove the tumor in the colon is universally accepted as an initial treatment, but the value of chemotherapy after that surgery (adjuvant chemotherapy) to keep cancer from recurring (coming back) is controversial. 

That is in part because most patients with stage II colon cancer are cured by surgery alone and don’t benefit from chemotherapy.

Chemotherapy is generally recommended after surgery for patients with stage III and IV colon cancers.

Radiation

Radiation therapy is not often used to treat colon cancer. When used to treat colon cancer, it is most often to treat tumors that have grown next to or into other organs. It may also be used to relieve side effects and improve quality of life.

Rectal Cancer

Surgery

If you have been diagnosed with rectal cancer, your stage will determine your course of treatment. If you have later-stage rectal cancer, you may be treated with radiation and chemotherapy prior to having surgery. 

If you have stage I, II, or III rectal cancer, your medical team may treat you with chemotherapy and radiation only, adopting a "watch and wait" approach regarding surgery.

According to NCCN Guidelines for Patients® Rectal Cancer 2022,

“Chemotherapy and radiation therapy may work so well that no cancer can be detected in the body. If this happens, some research suggests that having surgery does not always lead to better treatment outcomes. More recently, patients are being given the option to ‘watch and wait’ rather than have surgery. This is only an option for carefully selected patients who agree to close surveillance programs. Surveillance involves digital rectal exams, proctoscopy, and MRI of the pelvis with a rectal cancer staging technique. The benefits and risks of taking a watch-and-wait approach versus having surgery are not fully known.”

It’s critical to discuss with your doctor all of your surgical options and determine the goals of your treatment and surgery.

Chemotherapy

For some late-stage rectal cancer patients who are medically fit and can tolerate combined methods of therapy, treatment can consist of chemoradiation (chemotherapy and radiation) before surgery (adjuvant therapy), abdominal surgery, and/or adjuvant chemotherapy (chemotherapy given after recovery from surgery).

Patients who cannot tolerate chemoradiation at first, may go directly to surgery with no additional treatment, and then onto adjuvant chemotherapy and/or chemoradiation after surgery.

There are a variety of chemotherapy combinations that may be prescribed for stage IV patients.

Radiation

Radiation therapy may be recommended if you have been diagnosed with rectal cancer, depending on your stage and prognosis. Radiation therapy uses high-energy x-rays or other types or radiation to kill cancer cells. 

There are several types of radiation therapy. The intensity of radiation treatment and the way radiation therapy is given depends upon the type, location and stage of the cancer being treated.

Discuss all concerns and any quality of life issues with your medical team so that you can make an informed decision.

Clinical Trials for Rectal and Colon Cancers

Finally, clinical trials offer an opportunity for people with rectal and colon cancers to participate in studies that determine how well new medical approaches work in people. Clinical trials test new treatments like drug therapy, surgery, radiation, and combination procedures for rectal and colon cancers.

All treatments go through the clinical trial process before the Food and Drug Administration (FDA) approves them for public use. Trials are designed to protect participants, while collecting information to show whether or not an experimental treatment is safe and effective. 

It doesn’t matter: rectal cancer vs. colon cancer, Fight CRC has valuable resources and information to help you through diagnosis, treatment, surgery, and survivorship because no one fights alone.

Did You Know This About Colorectal Cancer?

Colorectal cancer is the only of the top five cancers not funded by the Department of Defense with a Congressionally-Directed Medical Research Program, and in fact, it is has to compete with approximately 20 other cancers for a fraction of the funding that breast cancer, prostate cancer, and kidney cancer received.

The National Comprehensive Cancer Network (NCCN) Guidelines for Patients® are separate for rectal cancer and colon cancer. NCI has a Rectal Cancer PDQ® Patient Version, but also a Colon Cancer PDQ®  Patient Version.

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