According to the World Health Organization (WHO), colorectal cancer is the second leading cause of cancer death each year around the world. In the United States alone in 2024, per the National Cancer Institute, there are expected to be over 150,000 new cases of colon cancer or rectal cancer and more than 50,000 deaths. The good news is that the rates of colorectal cancer are going down overall; however, incidence of colorectal cancer in younger people is increasing 1%-2% each year.

What to Know About Colorectal Cancer

Colorectal cancer is a type of gastrointestinal cancer that originates in either the colon or rectum. The vast majority of cases develop from precancerous polyps, a type of abnormal growth that forms on the inner lining of the large intestine. Eventually a polyp can be subject to mutation and become a cancerous tumor that can metastasize and send cancer cells to other vital systems around the body. While anyone from any age group can get colorectal cancer, it traditionally is more common in older adults.

Unlike some other types of cancer, colorectal cancer usually takes many years to develop from a polyp to cancerous tumor. During this lengthy timeline, there are often few, if any, symptoms that present. In fact, by the time symptoms begin to present, the cancer has likely developed to a more advanced stage where treatment options are limited. This is also the main reason why healthcare organizations like the American Cancer Society (ACS) recommend that all adults at average risk begin a regular pattern of screening tests at age 45 (and earlier for those at higher risk).

Risk Factors for Colorectal Cancer

Despite ongoing research over many decades, there is still much that is unknown about the cause of various types of cancer. Studies done to date, though, suggest that the majority of colorectal cancer cases are caused by lifestyle and environmental factors that are at least in part within the control of the individual. There is also some evidence that genetic factors, like a family history of colorectal cancer, additionally play a role. Below is a list of some factors that increase the risk of colorectal cancer:

  • Age: Colorectal cancer risk increases with age, with most cases diagnosed in individuals over 50. However, there has been a concerning trend of increasing rates of colorectal cancer in younger adults.
  • Family history: People with a family history of colorectal cancer or adenomatous polyps have a higher risk of developing the disease. The risk is particularly elevated if a first-degree relative (parent, sibling, or child) has been diagnosed.
  • Inherited syndromes: Certain inherited genetic conditions increase the risk of colorectal cancer, including Lynch syndrome (hereditary nonpolyposis colorectal cancer) and familial adenomatous polyposis (FAP).
  • Diet: Diets high in red and processed meats and low in fruits, vegetables, and fiber, have been linked to an increased risk of colorectal cancer. A poor diet can also lead to changes in the composition and diversity of the microbiome, which can influence the risk of cancer and a variety of gastrointestinal conditions.
  • Obesity: Being overweight or obese is also associated with a higher risk, and this is thought to be due in part to increased inflammation and changes in the hormones related to metabolism.
  • Sedentary lifestyle: An inactive lifestyle with little physical activity can also increase the risk of cancer; moreover, a lack of physical activity can further exacerbate the risk associated with obesity.
  • Smoking and drinking: Smoking and excess alcohol consumption are both related to increased risk of cancer and other negative health outcomes.

Symptoms of Colorectal Cancer

As noted above, the symptoms of colorectal cancer tend not to manifest during the earliest stages. Polyps themselves may grow without disrupting digestion in any way, and the symptoms typically don’t begin until a full tumor has formed. Below are some examples of symptoms that a patient may experience:

  • Bowel habits: Persistent changes in bowel habits, such as diarrhea, constipation, or changes in stool consistency, that last for more than a few days or weeks.
  • Abdominal pain: Abdominal pain, bloating, cramping, or general discomfort is common.
  • Rectal bleeding: Blood in the stool (either bright red or darker in color) or bleeding from the rectum, which may appear as blood on toilet paper after wiping.
  • Weight loss: Significant unintentional or unexplained weight loss that occurs without changes in diet or physical activity.
  • Fatigue: Persistent fatigue, weakness, or tiredness that is not relieved by rest and may be accompanied by other symptoms.
  • Incomplete evacuation: Sensation of incomplete evacuation after bowel movements or feeling that the bowel does not empty completely.
  • Nausea and vomiting: Nausea or vomiting may occur because of bowel obstruction or other complications of advanced colorectal cancer.

    Why Is Colorectal Cancer on the Rise Among Young People?

    Since at least the 1990s, incidence of colorectal cancer has increased among younger patients. Researchers still don’t know why these rates have been increasing, but it appears to be related to some of the same risk factors that affect the disease in general. For instance, overweight and obesity have also been increasing among young people over the same time period; additionally, the average American diet has tended to include more of the processed foods that seem to be related to increased cancer risk.

    Such dietary patterns may also negatively impact the gut microbiome, the community of microorganisms that live in the large intestine. Research suggests that changes to the microbiome might cause disruptions in numerous body systems as well as increasing the growth and spread of cancer. These disruptions to the microbiome may also cause other gastrointestinal problems that might otherwise be dismissed as mild symptoms. This could potentially lead to a missed early cancer diagnosis.

    Colorectal Cancer Prevention

    In light of not knowing the reason for increased rates of colorectal cancer in young patients, it is important for people of all ages to be mindful of the risk factors. Cancer prevention starts with adapting one’s lifestyle and reducing or eliminating any factors, and perhaps the easiest way to start is by making changes to diet and exercise habits. Anyone can start by choosing a diet that is high in fruits, vegetables, and whole grains and low in processed foods. Along with regular physical activity, this can help maintain a healthy weight and lower the chances of developing cancer.

    Another crucial part of preventing cancer is through colorectal cancer screening. Though there are several methods doctors may use, one of the most common approaches is colonoscopy. This involves feeding a thin tube with a camera into the colon so the doctor can directly visualize the inner lining of the colon. Doing this regularly from the age of 45 can help the doctor detect polyps or other abnormalities that might indicate a potential problem. People under the age of 45 with higher risk may need to start screening at an earlier age.

    Cancer Screening from Cary Gastroenterology

    It may not be totally clear why rates of colorectal cancer are higher for young people, but the best way to prevent cancer in general is to get screened. If you are 45 or older and haven’t had a cancer screening test yet, you should contact a gastroenterologist today. At Cary Gastro, our dedicated staff is passionate about providing the best digestive healthcare for our patients. If you would like to schedule a screening, please contact us today to request an appointment.