What is colon cancer?

Colon cancer is malignant cells found in the colon or rectum. The colon and rectum are parts of the large intestine which are part of the digestive system. Because colon cancer and rectal cancers have many features in common, they are sometimes referred to together as colon cancer.

Cancerous tumors found in the colon or rectum may also spread to other parts of the body.

Excluding skin cancers, colon cancer is the third most common cancer in both men and women.

The American Cancer Society estimates that about 140,000 colon cancer cases and about 50,000 deaths from colon cancer occur each year. The number of deaths due to colon cancer has decreased, which is attributed to increased screening and polyp removal and to improvements in cancer treatment.

Symptoms of colon cancer

The following are the most common symptoms of colon cancer; however, each individual may experience symptoms differently.

People who have any of the following colon cancer symptoms should check with their physician, especially if they are over 45 years old or have a personal or family history of the disease:

  • A change in bowel habits such as diarrhea, constipation or narrowing of the stool that lasts for more than a few days
  • Rectal bleeding, dark stools or blood in the stool
  • Cramping or gnawing stomach pain
  • Decreased appetite
  • Vomiting
  • Unintended weight loss
  • Weakness and fatigue
  • A feeling that you need to have a bowel movement that is not relieved by doing so

The symptoms of colon cancer may resemble other conditions, such as infections, hemorrhoids, and inflammatory bowel disease. It is also possible to have colon cancer and not have any symptoms. Always consult your physician for a diagnosis.

What are the risk factors for colorectal cancer?

Colon cancer risk factors may include:

Most people who have colon cancer are over the age of 45, but it can occur at any age

Race and ethnicity
African-Americans have the highest risk for colon cancer of all racial groups in the U.S. Jews of Eastern descent (Ashkenazi Jews) have the highest colon cancer risk of any ethnic group in the world

Colon cancer is often associated with a diet high in red and processed meats

Personal history of colorectal polyps
Benign growths on the wall of the colon or rectum are common in people over the age of 45 and may lead to colon cancer

Personal history of colon cancer
People who have had colon cancer have an increased risk for another colon cancer

Family history
People with a strong family history of colon cancer or polyps in a first-degree relative, especially in a parent or sibling before the age of 45 or in two first-degree relatives of any age, have an increased risk for colon cancer

Ulcerative colitis or Crohn’s disease
People who have an inflamed lining of the colon have an increased risk for colorectal cancer

Inherited syndromes
Familial adenomatous polyposis or hereditary nonpolyposis colon cancer, also known as Lynch syndrome can increase your risk for developing colon cancer

Type 2 diabetes

Other lifestyle-related factors:

  • Physical inactivity
  • Heavy alcohol consumption
  • Smoking
Methods of screening for colon cancer
Barium enema

Barium enema with air contrast involves a chalky liquid used to coat the inside of organs so they will show up on an X-ray and is administered into the rectum to partially fill up the colon. Air is then pumped into expanding the colon and rectum, and an X-ray of the abdomen is taken that can show strictures, blockages, and other problems.


Colonoscopy is a procedure that allows the physician to view the entire length of the large intestine and can often help identify abnormal growths, inflamed tissue, ulcers, and bleeding. It involves inserting a colonoscope, a long, flexible lighted tube in through the rectum up into the colon and allows the physician to see the lining of the colon, remove tissue for further exam and possibly treat some problems that are discovered.

CT colonography (virtual colonoscopy)

CT colonography (virtual colonoscopy) is a procedure that uses computerized tomography (CT) scans to examine the colon for polyps or masses. The images are processed by a computer to make a 3D model of the colon. Virtual colonoscopy is noninvasive but does require a small tube to be inserted into the rectum to pump air into the colon. If something abnormal is seen with this test, a standard colonoscopy will be needed as a follow-up.

Fecal immunochemical test (FIT)

Fecal immunochemical test (FIT) is similar to a FOBT, but doesn’t require any restrictions on diet or medications prior to the test.

Flexible sigmoidoscopy

Flexible sigmoidoscopy is a diagnostic procedure that allows the physician to examine the inside of a portion of the large intestine with a short, flexible tube that has a small video camera on the end called a sigmoidoscopy. The scope is inserted into the intestine through the rectum and blows air into the intestine to inflate it and make viewing the inside easier.

Fecal occult blood test (FOBT)

Fecal occult blood test (FOBT) checks for hidden blood in the stool and involves placing a very small amount of stool on a special card that is sent to a lab.

Early detection

Colon cancer screening guidelines from the American Cancer Society for early detection include:

Beginning at age 45, both men and women should follow one of the exam schedules below:

  • Fecal occult blood test or fecal immunochemical test every year
  • Flexible sigmoidoscopy every five years
  • Double-contrast barium enema every five years
  • Colonoscopy every 10 years
  • CT colonography every five years
What are the types of cancer in the colon and rectum?

A type of cancer called adenocarcinoma accounts for more than 95% of cancers in the colon and rectum and is usually what is meant by the term colorectal cancer. There are other types of cancer that can be found in the colon and rectum, but they are rare.

Types of cancer in the colon and rectum include:


Adenocarcinoma is a tumor that starts in the lining of internal organs; adeno means gland. These tumors start in cells with glandular properties, or cells that secrete. They can form in many different organs such as the lungs or breast. In colorectal cancer, early tumors start as small adenomatous polyps that continue to grow and can then turn into malignant tumors. The majority of colorectal cancers are adenocarcinomas.


Carcinoids are tumors that start in special hormone-producing cells in the intestine. They often cause no symptoms at first, and surgery is the usual treatment.

Gastrointestinal stromal tumors (GIST)

Gastrointestinal stromal tumors (GIST) are tumors that start in specialized cells in the wall of the digestive tract called the interstitial cells of Cajal. These tumors may be found anywhere in the digestive tract, although they rarely appear in the colon. They can be noncancerous, or benign at first, but many do turn into cancer. When this happens, they are called sarcomas. Surgery is the usual treatment if the tumor has not spread.


Lymphoma is cancer that typically starts in a lymph node (part of the immune system), however, it can also start in the colon, rectum or other organs.


Sarcoma are tumors that start in blood vessels, muscle or connective tissue in the colon and rectum wall.

Stages of colon cancer

When colon cancer is diagnosed, tests will be performed to determine how much cancer is present and if the cancer has spread from the colon or rectum to other parts of the body. This is called staging; it is an important step toward planning a treatment program. The stages of colon cancer are:

  • Stage 0—The cancer is found in the innermost lining of the colon or rectum.
  • Stage I—Cancer has spread beyond the innermost lining of the colon or rectum to the second and third layers. and has not spread to the outer wall or outside of the colon or rectum.
  • Stage II—Cancer has spread through into the wall or outside the colon or rectum to nearby tissue, however, the lymph nodes are not involved.
  • Stage III—Cancer has spread to nearby lymph nodes but has not spread to other organs in the body.
  • Stage IV—Cancer has spread to other parts of the body, such as the lungs.

Colon cancer treatment

If colon cancer is caught in the earliest stages, it is often very treatable. The dedicated team of experts at Baylor Scott & White Health is here for you. Any questions you may have about colorectal cancer treatment or clinical trials can be answered by your doctor.

Your treatment plan will be determined by your care team based on age, medical history, type and stage of colorectal cancer, and personal preferences.

Colon cancer treatment options may include:

Will my bowel function change after rectal cancer surgery?

It is possible that your bowel function may change after rectal cancer surgery. The rectum works normally to store bowel movements until it is time to pass them, so to do this it has the ability to stretch and store a larger volume than other parts of the large intestine.

When part of the rectum is removed, the left colon is used to replace the rectum. However, the left colon has a thick muscular wall that does not stretch to store stool. Instead, stool is stored in a long column in the colon, as a result, people may find that they cannot completely evacuate a bowel movement in one sitting. People can have the sensation of incomplete evacuation and may have to have multiple smaller bowel movements throughout a short period of time to empty the column of stool. This syndrome is called Low Anterior Resection Syndrome. In most cases, the body adapts after surgery to improve storage and evacuation. In rare cases, this can be a severe problem.

Locations for colon cancer care in Texas


Colorectal Cancer Research and Treatment Center, located at Baylor University Medical Center, part of Baylor Scott & White Health, is dedicated to providing advanced therapies, innovative research, minimally invasive treatments and valuable resources to patients affected by colorectal cancer.

Round rock

Baylor Scott & White Cancer Center - Round Rock, located in Round Rock, Texas, offers complete, personalized care and robust support patients need on their journey from gastroenterology cancer patient to cancer survivor. As part of the Baylor Scott & White System, our Round Rock Cancer Center is part of the largest network of hospital-based cancer programs in Texas and is accredited by the Commission on Cancer.


Baylor Scott & White Vasicek Cancer Treatment Center – Temple, located in Temple, Texas, offers an integrated care team for gastrointestinal cancer. The multidisciplinary group of physicians on the medical staff has the specialized training and the experience necessary to diagnose, evaluate and treat cancers in the GI tract.