Important Facts About Colonoscopies and Colon Cancer

March 13, 2026

Colorectal cancer is the second leading cause of cancer-related death in the United States. However, its incidence and mortality can be significantly reduced through routine colonoscopy screening, according to Jay Fenster, MD, Chief of Gastroenterology at Episcopal Health Services.

“Colon cancer often begins with abnormal cells that form growths known as polyps,” explains Dr. Fenster. “Regular colonoscopy screening provides an opportunity to identify and remove these polyps before they progress to cancer.” While the risk of colorectal cancer increases with age, it has recently become a more critical health concern for younger patients, and is currently the leading cause of cancer death in patients under age 50.

Research indicates that a significant number of adults nationwide are not adhering to recommended colon cancer screening guidelines. This may be due to the absence of symptoms or apprehension about the procedure itself. To address these concerns, Dr. Fenster outlines what colonoscopies are, who should receive them, and what patients can expect before, during and after the procedure.

Colon Cancer Prevention and Treatment

A colonoscopy is a medical procedure used to detect, diagnose, and, in some cases, treat colorectal cancer. During the procedure, a colonoscope—a thin, flexible tube equipped with a light and camera—is inserted into the large intestine to evaluate for lesions or abnormalities.

The colonoscope provides live video and captures detailed images that are reviewed by a gastroenterologist to identify abnormalities such as polyps. If polyps are found, they can often be removed painlessly during the same procedure.

Colonoscopy screening is recommended for individuals who:

• Are age 45 or older, as colorectal cancer risk increases with age
• Have a family history of colorectal cancer
• Have an inherited condition that increases colon cancer risk, such as colorectal polyposis syndromes
• Have been diagnosed with inflammatory bowel disease, including ulcerative colitis or Crohn’s disease

Approximately 75 percent of colorectal cancer cases are considered sporadic, meaning they occur without identifiable risk factors. For this reason, the American Cancer Society recommends routine screening for all adults without a family history, beginning at age 45, to allow for early detection and removal of precancerous polyps.

Recognize the Signs of Colon Cancer

While colonoscopies are most effective as a preventive tool, some polyps may progress to cancer and cause symptoms, including:

• Rectal bleeding or blood in the stool
• Changes in bowel habits
• Unexplained or sudden weight loss
• Persistent or significant abdominal discomfort

Anyone experiencing these symptoms should seek immediate medical attention.

Misconceptions Prevent Detection

A diagnosis of colon cancer is not a death sentence. Advances in screening and treatment have made colorectal cancer highly treatable, particularly when detected early. Colonoscopy plays a critical role in both prevention and early intervention.

Another common concern is discomfort during the procedure. In reality, colonoscopies are generally well tolerated, relatively brief, and performed under conscious sedation to ensure patient comfort.

Proper Preparation is Important

Adequate preparation is essential to ensure accurate visualization of the colon. Preparation typically includes:

• Avoiding weight-loss medications during the week of the procedure
• Temporarily discontinuing blood thinners, if approved by a cardiologist or neurologist
• Following a low-fiber diet in the days leading up to the procedure
• Consuming a clear liquid diet the day before the colonoscopy
• Completing bowel cleansing with a prescribed laxative solution or pills, usually taken in two doses—one the afternoon or evening before and the second on the morning of the procedure

What to Expect During Your Colonoscopy

During a colonoscopy, patients lie on a stretcher and receive intravenous sedation. Carbon dioxide is used to inflate the colon for improved visualization and is rapidly absorbed by the body, minimizing post-procedure discomfort. The gastroenterologist examines the colon, removes polyps, takes biopsies of suspicious areas and cauterizes any bleeding sites as needed.

The procedure typically lasts about 20 minutes but may take longer depending on individual anatomy or removal of polyps.

Complications Are Relatively Rare

Colonoscopy is a safe procedure. However complications such as bleeding, infection or perforation can occur in rare cases.

Recovery Takes Approximately 24 Hours

After the procedure, patients are monitored in a recovery area and offered light refreshments. The gastroenterologist will review preliminary findings and discuss next steps before discharge. While many results are available immediately, biopsy analysis may take up to one week.

Patients should not drive or make important decisions for at least six hours following the procedure and must arrange transportation home. Most individuals can resume their normal activities and diet the following day.

If you are age 45 or older or are experiencing symptoms associated with colorectal cancer, book your colonoscopy at EHS with a referral from your primary care physician by calling 718-EHS-DOCS (347-3627). If you do not have a primary care physician, call 718-EHS-DOCS (347-3627) to book an appointment. Visit ehs.org/colonoscopy to learn more!