Colorectal cancer, or colon cancer, is the third most common cancer diagnosed and the second leading cause of cancer-related deaths in the United States. Most colorectal cancers begin as a non-cancerous polyp, which is a growth within the inner lining of the colon or rectum. Over time and without removal, these polyps develop into cancer. Colorectal cancer also can develop from a condition called dysplasia, which is where cells in the lining of the colon or rectum appear abnormal.

What are the symptoms?

People with colorectal cancer often do not have symptoms immediately. By the time symptoms occur, the cancer may have grown or spread to other organs, making the cancer more difficult to treat. Common symptoms include:

• Bowel changes lasting longer than a few days, such as diarrhea, constipation or a feeling that your bowel is not empty after a bowel movement

• Bright red or very dark blood in the stool

• Constant tiredness

• Ongoing gas pain, bloating, fullness or cramps

• Stools that are thinner than usual

• Stools that look slimy or have mucous on them

• Unexplained weight loss

• Vomiting

What is a colonoscopy?

Colonoscopy is a diagnostic procedure that doctors use to:

• Examine the entire length of the large intestine

• Identify problems with the colon, such as early signs of cancer, inflamed tissue, ulcers and bleeding

• Screen for colorectal cancer

During a colonoscopy, a long, flexible and lighted tube called an endoscope is inserted through the rectum into the colon. This enables the doctor to irrigate, suction, inject air and access the bowel with surgical instruments. The doctor may remove tissue or polyps for further examination and possibly treat any areas of concern that are discovered.

How can a screening prevent cancer?

Colorectal cancer develops very slowly. It takes as long as 10 to 15 years for a polyp to change into cancer. With regular screenings, polyps can be removed before turning into colorectal cancer.

What screenings can find polyps and cancer?

There are many screenings that can detect polyps and cancer, including flexible sigmoidoscopy, CT colonography and colonoscopy. Colonoscopy and CT colonography are the only screenings that allow a view of the entire colon, and biopsy and removal of existing polyps are only possible with a colonoscopy. Colonoscopy is recommended once every 10 years, or sooner if polyps are found, and one of these other screening methods are recommended every five years. There are also non-invasive stool tests that can detect colon cancer. The FIT test is recommended once a year and Cologuard is recommended every three years.

Are screenings painful?

Depending on the type of screening, there may be minimal discomfort. Screening techniques have advanced like other medical technologies, and today’s screenings are not as uncomfortable as a decade ago.

Who should be screened?

The American Cancer Society recommends:

• Patients without risk factors begin regular screening at age 50

• African Americans without risk factors begin screening at age 45

• Patients with a first-degree relative diagnosed between age 50 and 60 begin screening at age 40 or 10 years prior to the diagnosis of the first-degree relative

A primary care doctor can help a patient determine risk factors, when to begin screenings and answer questions.

Alexis Rossland is a gastroenterology provider at Sanford Clinic in Bismarck. She graduated from University of Alaska Fairbanks with a bachelor's degree in biology and earned her bachelor's degree in nursing at Creighton Medical Center in Omaha, Neb. Alexis received her master's degree in nursing from the University of Nebraska Medical Center in Omaha, Neb.