What are the Odds You'll Get Colorectal Cancer? Here are the Facts

This article was reviewed by our Baystate Health team to ensure medical accuracy.

Holly K. Sheldon, MD Holly K. Sheldon, MD View Profile
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First, the bad news:

  • Colorectal cancer is the third most common type of cancer in men and women.
  • Every 3.5 minutes, someone is diagnosed with colon cancer.
  • Colorectal cancer is the second-most common cause of cancer death in men and women.

Now the good news: Colorectal screenings—especially colonoscopies—literally save lives.

And more good news: Colonoscopies are covered by insurance.

So, while anyone can get colorectal cancer, anyone (including you) can also get a screening to prevent it.

Colorectal cancer: causes and risks

As the name implies, colorectal cancer (CRC) is a cancer that occurs in the colon or the rectum. Here, Dr. Holly Sheldon, a colorectal surgeon at Baystate General surgery, explains the causes and risks of the disease.

“CRC often begins as a polyp, or growth, on the lining of the colon or rectum,” she explains. “While not all polyps are cancerous, the most common type, called an adenoma, are precancerous. If undetected, adenomas can develop into cancer and grow into and even through the lining of the colon or rectum, potentially spreading cancer to other organs and throughout the body.

“Fortunately,” she notes, “adenomas are usually slow growing, taking seven to ten years to become cancerous. The problem is they are asymptomatic, meaning you can live with one for years with no idea it’s there. Once they are large enough to cause symptoms, most often bleeding, there is a higher likelihood of malignant potential. The take-away here is that if you stay current with screenings, there’s an extremely good chance any adenoma you have will be caught well before it become cancerous.”

While CRC can occur in anyone at any age, there are certain factors that put some individuals at greater risk of developing it.

“There are both modifiable and non-modifiable risk factors that impact how likely someone is to develop CRC,” says Sheldon.

Colon Cancer Risk Factors You Can’t Control

The non-modifiable risks factors include:

  • A family history of colon cancer or polyps
  • Inflammatory bowel disease
  • Abdominal radiation exposure
  •  Age – occurs most often after age 50
  • Gender – men are more likely to have CRC
  • Ethnicity – higher incidence in African Americans
  • Other health conditions including diabetes, cystic fibrosis, or a suppressed immune system due to having received an organ transplant

Colon Cancer Risk Factors You Can Control

Modifiable risk factors, meaning things you can change within your lifestyle, that are known to contribute to CRC include:

  • Smoking
  • Being overweight
  • Diet that includes alcohol, red meat, processed meat, and low consumption of fruits, vegetables, and fiber
  • Inactivity

How to Prevent Colon Cancer

Sheldon notes, “The impact of modifiable risk factors on an individual’s likelihood of developing CRC is significant. In fact, studies have found that making lifestyle modifications, like losing weight, quitting smoking, limiting red meats, etc., can reduce your risk of developing CRC.”

Recognizing Signs of Colon Cancer

In its earliest stages, CRC may not cause symptoms. As it progresses, common symptoms include:

  • Blood in stool
  • Change in bowel habits
  • Constipation or diarrhea
  • Tender, persistent abdominal pain
  • Narrow stool
  • Unexplained weight loss
  • Fatigue
  • Anemia

“Unfortunately,” says Sheldon, “Most CRCs, roughly 70-90%, are diagnosed after symptoms are experienced.” Patients who present with symptoms tend to have higher death rates, and if they don’t die from it, there’s a strong likelihood of metastatic disease or recurrence. All of this points to the importance of screenings.

Colon Cancer Screening

Screening colonoscopies are used to look for colorectal cancer in people who have no symptoms. The American Cancer Society recommends that anyone at average risk for CRC begin regular screenings at age 45. Those at high risk may need to begin screening earlier, get screened more frequently, or get specific tests. If you fall in the high-risk category, speak to your doctor about what makes sense for you.

Sheldon notes that there are basically two types of screenings: visual and stool-based tests.

Visual Colon Cancer Screening Tests

“Far and away, a visual screening is the most effective method for spotting precancerous growths, removing them and thereby preventing cancer.” The one most people are familiar with is a colonoscopy. Covered by insurances, colonoscopies can be performed with or without anesthesia, and are 90-100% effective. She adds, “A lot of patients worry about the bowel prep required in advance of the procedure. It has come a long way from a few years ago and is a lot more palatable. The prep basically cleans out the colon so the doctor has a clear view of what’s going on and can remove any polyps that may be present.”

The other visual exam option is a CT colonography. The procedure uses a CT scan to look for polyps and growths in the colon. While it is less invasive than a colonoscopy, it also requires bowel prep and the colon and rectum must be inflated with air or carbon dioxide during the exam to provide the doctor with a clear view. In addition to the required radiation exposure, other drawbacks of colonography include the fact that small flat polyps may not be visible in a scan and the procedure may not be covered by insurance. Also, if a polyp is identified, a colonoscopy is recommended to assess and treat.

Stool-Based Colon Cancer Screening Tests

Relatively new stool-based tests offer a less invasive screening option that can be performed at home. The three most common types of tests include:

  • Fecal immunochemical test (FIT)
  • Fecal occult blood testing (FOBT)
  • Stool DNA test

All three rely on the patient to collect and ship a fecal sample to a lab where it’s examined for either hidden blood or abnormal DNA associated with polyps and colorectal cancer. While none require bowel prep, FOBT requires three blood samples in addition to a stool sample.

Sheldon cautions, “While at-home colon cancer tests offer some conveniences, colonoscopies are better at finding pre-cancer and cancer cells, and offers the possibility of removal or biopsy at the same time.”

The right screening is the one you do

Sheldon encourages everyone to speak to their provider about when is the right time to begin regular screenings and which option makes the most sense for the individual.

Talk to your primary care provider about when is the right time for you to have a colonoscopy. Learn more about colon cancer screening.

Baystate Experts Discuss

Colorectal surgeons Dr. Holly Sheldon and Dr. Ziad Kutayli discussed colon cancer risk in a live virtual event with Q&A. Register for an upcoming event to learn more.

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