Colorectal cancer is one of the most common cancers in the U.S. It is important to understand how colorectal cancer functions in the body and how it is diagnosed so that you can feel confident in your care if you or someone who know develops this disease.

Colorectal cancer 101

Ninety to 95 percent of all colorectal cancers are adenocarcinomas, which is a cancer that begins in cells that make and secrete fluids such as mucus. These cells are found in glandular tissue.

To better understand what an adenocarcinoma is, consider the word: Adeno means gland; carcinoma is a malignant tumor. Although these tumors are malignant, they generally start from adenomas – polyps that are not cancerous. The bigger the adenoma is, the more likely it is to become cancerous.

Colon polyps are a common occurrence. In fact, 25 percent of people over the age of 50 have polyps. It is important to remove these polyps to ensure they do not become cancerous.

Diagnosing colorectal cancer      

If you are being examined for colorectal cancer, the first thing your doctor will do is review your medical history. He or she will conduct a thorough medical exam and then may conduct one or more of the following tests:

  • Digital rectal exam – This exam checks the rectum for lumps or abnormalities. About half of colon cancers can be detected in this way.
  • Fecal occult blood test – Blood in the stool can be an indicator of colorectal cancer. Your stool may also contain blood for other reasons not connected to colorectal cancer. If you experience blood in your stool, contact your healthcare provider.
  • X-ray of the large intestine or barium enema – An X-ray provides a picture of the colon and can help identify any polyps.
  • Colonoscopy – A colonoscopy is used to examine the bowel’s interior surface for abnormalities like polyps.
  • Biopsy – A biopsy allows the doctor to remove a tissue sample to then be sent to a pathologist for examination.
  • Virtual colonoscopy – This is a type of CT scan. It uses computer software along with CT imaging to examine the colon for polyps.

Stages of colorectal cancer

  • Stage 0: This is an extremely early stage. Abnormal cells are found only in the superficial layer of the colon wall. Stage 0 is also called carcinoma in situ.
  • Stage 1: This is an early stage. Cancerous cells have been found in the muscular layer of the colon wall, however, it has not spread beyond the colon wall.
  • Stage 2: Cancer has spread through the muscle layer of the colon wall to the outermost layer of the colon wall, but has not spread to the lymph nodes.
  • Stage 3: Cancer has spread to nearby lymph nodes but not to other parts of the body.
  • Stage 4: Cancer has spread beyond the colon to other parts of the body, most often the liver and lungs. This is an advanced stage.

Sarah Cannon, the Cancer Institute of HCA Healthcare, recommends consulting your physician if you are 45 years of age or older to determine the right screening test for you. Evidence-based options may include a colonoscopy at 10-year intervals or a fecal immunohistochemistry test (FIT) annually. Speak with your healthcare provider about the right course of action for you.

Speak with your healthcare provider about the right course of action for you.

Understanding colorectal cancer

Screening for colon cancer

The American Cancer Society updated their guidelines for colorectal cancer screenings, dropping the age for an initial screening from 50 to 45. While that might make many of us groan, there are a number of screening options that are effective—and actually easy—for those with normal risk.

Five Colorectal Cancer Facts

  1. Colorectal cancer is the second leading cause of death among men and women combined.
  2. Thanks to increased screening tests, it’s the third most commonly diagnosed cancer
  3. However, 1 in 3 people are not up-to-date with their screening
  4. And 23 million adults in the U.S. have not had the recommended screening
  5. A shocking 60 percent of deaths by colon cancer could be prevented with screening

A study released in 2014 showed that colon cancer incidence rates have dropped 30 percent in the U.S. among adults ages 50 and older due to the widespread use of colonoscopy screenings. The study also showed a large decrease in colon cancer rates among those ages 65 and older. The bottom line, no pun intended, is that screening saves lives.

If your doctor recommends a screening, or you’re looking for easier options, we’ve pulled together a guide to colorectal screening.

Colorectal screenings fall into two categories, stool-based tests and visual exams. Stool-based tests check your feces for signs of cancer. These tests are less invasive and easier to have done, but they need to be done more often. Visual exams look at your colon and rectum, using a scope or with imaging, for any signs of abnormalities.

Note that any abnormal test results are usually followed up with a colonoscopy, and not all tests are recommended for those with digestive issues or colon cancer symptoms.

Stool-Based Tests

Fecal immunochemical test (FIT):

Small amounts of stool are collected on cards at home and then sent or taken to a lab. The test looks for trace amounts of blood resulting from cancerous spots.


  • No bowel prep
  • Sampling can be done at home


  • Needs to be done each year
  • Can miss some cancers
  • Sometimes gives false-positives

Guaiac-based fecal occult blood test (gFOBT):

This fecal test can also be done from home, but it tests for hidden blood in the stool through a different, chemical way than the FIT test.


  • No bowel prep, but some patients are advised to cut out non-steroidal anti-inflammatory drugs (NSAIDs), Vitamin C supplements, and red meat in advance of the test.
  • Sampling can be done at home or during an exam


  • Needs to be done each year
  • Can miss some cancers
  • Sometimes gives false-positives

Stool DNA test:

This at-home collection test looks for abnormal sections of DNA from cancer or polyp cells.


  • No bowel prep
  • Sampling can be done at home


  • Needs to be repeated every 3 years
  • Can miss polyps and some cancers
  • Can give false-positives
  • Still new, so insurance coverage may be an issue

Visual Exams


A doctor looks at the entire length of your colon and rectum with a colonoscope, a flexible tube with a light and a small video camera on the end. Special instruments can be passed through the colonoscope to biopsy or remove any suspicious-looking polyps.


  • Can biopsy and remove polyps during the test
  • Only needs to done every 10 years
  • Can help find other diseases


  • The colon and rectum must be clean for the doctor to see the inner lining, so test prep – using pills, fluids, and/or enemas – is required
  • Light sedation during the test means you’ll need a full day to have the test, a driver to take you home, and rest after the procedure

CT Colonography (also called virtual colonoscopy):

This test uses a CT scan of the colon and rectum to create 2D and 3D pictures for the doctor to examine.


  • No sedation necessary
  • Needs to be done every 5 years


  • Like a regular colonoscopy, full bowel prep is needed
  • Air must be pumped into the colon during the scan, which may cause cramps

Flexible Sigmoidoscopy:

Similar to a colonoscopy, this test only looks at a portion of the colon and rectum but requires little bowel prep and usually no sedation.


  • Usually doesn’t require full bowel prep or sedation
  • Done every 5 years


  • Only looks at about a third of the colon

There’s no two ways about it… If you’re age 45 or older, talk with your doctor about your options for colon cancer screening, and join countless men and women whose lives have been saved from this devastating disease.