The American Cancer Society warns that the lifetime risk of colorectal cancer is 1 in 23 for men and 1 in 25 for women. And although the rates of diagnosis have continued to drop for older adults, the rates for people under the age of 55 have been increasing since the 1990s. While those odds may seem pretty good, it’s important to remember that colorectal cancer usually takes years for symptoms to develop; and by then the treatment options may be more limited. For this reason, doctors recommend getting screened for colon cancer at regular intervals.1

Facts About Colorectal Cancer

Colorectal cancer is the term for the type of cancer that starts in either the colon or the rectum; while colon cancer and rectal cancer are technically separate conditions, they both are similar in terms of progression, staging, and treatment. Colorectal cancer is one of the most common types of cancer worldwide and a leading cause of cancer-related deaths. In fact, it is estimated that over 50 thousand Americans will die of colorectal cancer in 2024. There are also estimated to be over 150,000 new cases diagnosed this year.

The development of colorectal cancer often begins innocuously, with the appearance of small growths called polyps on the inner lining of the colon or rectum. Most of the time, these abnormalities are benign and the patient may live their whole life without them becoming cancerous. In some cases, however, polyps can start to experience dysplasia, a state of abnormal cell growth that serves as an early warning sign of precancerous changes. This is where genetic mutations take place that can lead to runaway growth of cancer cells.

What began as a seemingly harmless polyp begins to divide and grow in an uncontrolled way, until a tumor has formed that is embedded in the lining of the large intestine. As the cancer progresses, malignant cells will eventually break free from the primary tumor and start to spread to other parts of the body via the bloodstream. If untreated, these cancer cells will invade other organs and create new sites of cancer growth. This whole process can take years or even decades to move from polyp to precancerous polyp to cancer.

Risk Factors for Colorectal Cancer

As with other types of cancer, doctors and researchers don’t precisely know what causes colorectal cancer. Unlike other types, however, genetic factors appear to be significantly less important in its development. Generally speaking, people who are over the age of 50 are at a higher risk; it is also slightly more likely in men than women. Most of the other factors are rooted in lifestyle choices that anyone can change:

  • Obesity: Being overweight or obese, especially with a high concentration of abdominal fat, has been associated with an increased risk of colorectal cancer. This may be due to the effects of excess body fat on hormonal levels, inflammation, and insulin resistance, which can contribute to the growth and progression of cancer cells.
  • Diabetes: A condition often related to obesity is type 2 diabetes, an endocrine disease that is characterized by insulin resistance and hyperinsulinemia; these factors similarly increase inflammation and other forces that may drive abnormal cell growth in the colon.
  • Diet: One risk factor that is especially relevant in the United States is diet; the average American diet is high in foods that have been associated with colorectal cancer as well as numerous other negative health outcomes. Examples of such foods include red and processed meats as well as meals that are low in fiber, fruits, and vegetables. Some of the compounds found in processed meats, for example, may contribute to the formation of carcinogenic compounds in the gastrointestinal tract. Additionally, a diet low in fiber and phytochemicals from fruits and vegetables may also play a role in cancer development.
  • Smoking: Smokers have a higher risk of developing colorectal cancer compared to non-smokers because of the carcinogenic compounds found in tobacco smoke; these compounds can damage DNA and contribute to the development of cancerous cells in the colon and rectum.
  • Alcohol: Excessive alcohol consumption, particularly heavy or long-term use, can also increase the risk of colorectal cancer. Alcohol is thought to contribute to cancer development by damaging cells, altering hormone levels, and potentially interacting with other risk factors (like a diet high in red meat).
  • Physical activity: Another aspect of regular life that can have an impact on cancer risk is the amount of regular physical activity. Sedentary lifestyles with little exercise or other movement has been linked to an increased risk of colorectal cancer. Regular exercise may help reduce the risk by improving insulin sensitivity, reducing inflammation, and promoting healthy bowel function.

Ways to Diagnose Colon Cancer

Since the symptoms of colorectal cancer don’t present until after it has already been developing for years, early detection relies on other methods. Arriving at a cancer diagnosis usually involves a combination of screening tests, physical examinations, imaging studies, and tissue biopsies:

  • Stool tests: One option for early detection is to look for traces of blood in the stool, which may indicate polyps or a tumor in the colon. The two main types are the fecal occult blood test (FOBT) and the fecal immunochemical test (FIT).
  • Colonoscopy: The most well-known imaging test associated with colorectal cancer is the colonoscopy. The procedure involves inserting a flexible tube with a camera (colonoscope) into the rectum to visually examine the entire large intestine for polyps or abnormal growths. In some cases a sigmoidoscopy is used to only examine the lower part of the colon.
  • Imaging tests: Oncologists often use imaging tests like X-rays and CT scans to investigate the abdomen in order to look for lesions or other abnormalities. Other diagnostic tests, like a PET scan (positron emission tomography) can detect cancer cells by looking for areas of increased metabolic activity.
  • Biopsy: If polyps or other suspicious growths are found during a colonoscopy, the doctor may remove a tissue sample for examination under a microscope. The test results from a biopsy can confirm the presence of cancer cells and provide information about the type and stage of the cancer.
  • Blood tests: Usually after colorectal cancer is diagnosed, additional blood tests may be performed to clarify the extent of the disease. Examining a blood sample can provide helpful information like the state of liver function, the presence of anemia, a person’s complete blood count (CBC), or the levels of the tumor marker CEA (carcinoembryonic antigen).

    Guidelines for Colorectal Cancer Screenings

    Catching colorectal cancer at an early stage is critically important since waiting for symptoms to present can severely limit the treatment options. That’s why the American Cancer Society and other medical organizations recommend that average risk individuals start regular screenings at age 45 and continue through age 65. People with a family history of colorectal cancer, or are at higher risk for any reason, should start the process earlier and get screened more frequently. After the age of 85, screening is no longer recommended.

    Schedule a Colorectal Cancer Screening Test

    Colorectal cancer is a serious concern for older adults, but it has also become more common in adults under 55. The only way to know for sure that you don’t have it is to get screened. At Cary Gastro, we are dedicated to providing excellent digestive healthcare, including the kinds of screenings that can detect cancer early. If you are 45 or older and haven’t been screened yet, please contact us today to request an appointment.


    1    https://www.cancer.org/cancer/types/colon-rectal-cancer/about/key-statistics.html