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Colon Cancer Screening Tests

Colorectal cancer is a type of cancer that develops when abnormal cells in the colon or rectum divide uncontrollably and form a malignant tumor. Most colorectal cancers begin as abnormal growths or lesions that appear as raised polyps in the colon.

Colorectal cancer is the second leading cause of cancer-related death for men and women in the United States. Colon cancer survival rates dramatically increase when detected early, often when there are no clinical symptoms. The five-year survival rate is 91% in those with early, localized disease (Stage I or II) and 14% in those with metastatic disease (Stage IV).

In the US, colon cancer is most frequently diagnosed in adults aged 65–74 years, but the rates of colon cancer are decreasing in older age groups and increasing among younger generations. The reason for the increased incidence of colon cancer in younger people is unknown. Still, risk factors such as inherited conditions, family history, inflammatory bowel disease, smoking, heavy alcohol use, obesity, and physical inactivity could contribute.

Expert medical groups recommend that colon cancer screening begin at age 45 and continue to age 75. For those aged 76–85, the decision should be based on health, life expectancy, prior screening results, and consultation with their doctor. The frequency of screening depends on the type of screening and the patient’s risk factors.

Several screening tests are available to detect colon cancer before symptoms begin (when it is more treatable):

  • Stool tests: Since polyps and colorectal cancers can bleed, stool tests check for tiny amounts of blood in stool that cannot be detected visually. The patient collects stool samples using a kit, which is then sent to a laboratory for testing. Cologuard is a well-known brand of this type of test. 92% of colon cancers are detected when atypical DNA and traces of blood are found in the stool. A colonoscopy should be done following positive findings, and screening should be completed every 1–3 years.
  • Direct visualization tests: With these tests, a tube is inserted into the rectum to expand the colon and visualize the lining more clearly. A colonoscopy is the most common direct visualization test in the US, followed by virtual colonoscopy (a CT scan of the colon from outside the body) and sigmoidoscopy (a lighted tube inserted into the rectum and sigmoid colon to view and remove tissue). Polyps found during a colonoscopy are removed and sent for biopsy to determine if cancer is present. Colonoscopies should be done every 10 years unless a risk factor is present; sigmoidoscopies every 5–10 years, depending on risk factors; and virtual colonoscopies every 5 years.
  • Blood-based tests: Blood tests look for biomarkers shed into the blood from colon cancer. The SHIELD blood test analyzes plasma DNA for certain changes, including the presence of harmful gene variants. This test is intended for colorectal cancer screening in individuals aged 45 years or older who are at average risk for colorectal cancer. Average risk is defined as those who do not have symptoms and do not have an increased risk for developing colorectal cancer. It is not intended for individuals at high risk, such as those with a prior diagnosis of colorectal cancer, inflammatory bowel disease, a family history of colorectal cancer in a parent, brother, sister, or child, or an inherited risk of developing colorectal cancer. It is not intended as a replacement for diagnostic colonoscopy or surveillance colonoscopy in high-risk individuals.

No colorectal screening is perfect, but screening tests can help detect the possibility of cancer in early stages. A positive result does not mean you have colorectal cancer, but it raises concern that colorectal cancer or pre-cancer could be present, and additional follow-up is needed.

Medicare Part B covers several colorectal cancer screening tests because they are preventive services. If you have other types of insurance, check with your provider to see what is covered. There may be a co-pay involved.

On Sunday, December 14, from 8 AM to 1:30 PM, St. Therese will host a SHIELD Colorectal Cancer Screening Blood Test event in the Gathering Space. A representative and staff from the company will be at the church to draw blood and send it for testing. A member of our Health Ministry, Theresa Emch, NP, will also be on-site to assist and provide patient information. You can RSVP with the Parish Secretary or Marilyn Cito, Parish Nurse, at 586-254-4433 or Marilync@stol.church. Walk-ins are welcome, too!

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