Colorectal Cancer Signs and Screenings

Shannon Simmons, MD
Colorectal Cancer Screening

Colorectal cancer (CRC) is a type of cancer that begins in the large intestine or colon. The colon is the last part of the gastrointestinal (GI) system and serves to absorb nutrients and eliminate feces.

CRC most commonly starts as a precancerous growth, or polyp, that grows slowly over years in the colon. CRC generally forms on the inner lining of the colon, but it can also grow through the wall of the colon and spread to other organs.

How common is colorectal cancer?

Colorectal cancer is the second leading cause of cancer deaths in the United States. The American Cancer Society estimates 147,950 new diagnoses of colorectal cancer in 2020. CRC affects men and women equally, but a larger number of men are diagnosed with rectal cancer.  

Is CRC occurring more often in younger people?

This is true. From 2009 to 2013, CRC increased by 1.6% per year in adults under 50 years old according to SEER data. The reason for this increase is unclear; however, it may be related to diet, obesity and sedentary lifestyles. There are multiple ongoing studies trying to determine the underlying causes.

What are the signs and symptoms of colorectal cancer?

Most early colorectal cancers have no symptoms. As CRCs grow, they can bleed and cause a low red blood cell count, known as anemia. Other symptoms of CRC include a change in bowel habits (such as new constipation), rectal bleeding, dark stools (called melena, due to slow internal bleeding), abdominal pain or unintentional weight loss.

Why is screening so important?

Quite simply, colorectal cancer can be prevented through screening. Because there are typically no signs of CRC in its earliest stages, that is why screening tests like colonoscopy are so important -- because they can identify cancers early, before symptoms appear and when they are most treatable.  Successful screening can identify precancerous polyps and your physician can remove them before they become cancer.

What are the guidelines for screenings?

Most guidelines recommend starting colon cancer screening at age 50 for individuals with average risk of CRC. However, newer recommendations suggest screening start in the 40s for average individuals. Patients with risk factors, such as family history of CRC, inflammatory bowel disease or certain genetic disorders, may need screening even earlier. Talk with your doctor about what is most appropriate for you.

Healthcare providers agree that the best screening test for colon cancer is a colonoscopy, as it can not only detect precancerous polyps, but also remove them and effectively prevent cancer development. There are other less invasive modalities available such as Cologuard or FIT stool testing, which test stool samples for signs of cancer, or computed tomography (CT) colonography, which can potentially visualize polyps as well.

While there are other screening methods, colonoscopy is the only one that can both diagnose and remove early forms of cancer -- CRC screening can directly save lives. Your doctor can talk with you about the best screening method for you.

Visit our website for more information on colonoscopy.

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