What is Colorectal Cancer?
Colorectal cancer originates in the colon or rectum, often developing from polyps, which are abnormal growths on the inner lining of these organs. The American Cancer Society estimates there will be 152,810 new cases of colorectal cancer in 2024 for men and women combined. This will make colorectal cancer the 4th most common cancer by type. However, the outlook is grim as it is estimated that 53,010 people will lose their lives from colorectal cancer in 2024, making it the 2nd leading cause of cancer-related deaths. While there has been a decline in new colorectal cancer diagnoses among older adults since the mid-1980s, largely due to increased screening and changes in lifestyle-related risk factors, there is a troubling upward trend in colorectal cancer incidence among individuals under 50 years of age. This is why routine colorectal cancer screenings and monitoring for symptoms are so important. Age, sex, family history, and personal medical history can influence your cancer risk as well.
Modifiable Risk Factors for Colorectal Cancer
Overweight or Obesity: Being overweight increases your overall risk of cancer and raises the risk of colorectal cancer. Maintaining a healthy weight through a balanced diet, limited sedentary behavior, and regular physical activity can help you reduce the risk.
Type 2 Diabetes: Individuals with type 2 diabetes mellitus are at a higher risk of developing colorectal cancer, possibly due to high insulin levels.
Certain Dietary Habits: Long-term consumption of a diet high in red meats (such as beef, pork, lamb, or liver) and processed meats (like hot dogs and some lunch meats) can raise the risk of colorectal cancer. Cooking meats at very high temperatures (frying, broiling, or grilling) can create chemicals called carcinogens that might increase cancer risk. Low blood levels of vitamin D may also elevate the risk. The recommended diet includes plenty of fruits, vegetables, and whole grains, and limits or avoids red meats, processed foods, and sugary drinks.
Smoking: Smoking is a well-known risk for the development of lung cancer, but it can also increase your chance of developing colon polyps. Those who smoke are also more likely to develop and die from colorectal cancer than non-smokers.
Alcohol Use: Colorectal cancer has been linked to moderate to heavy alcohol use. Even light-to-moderate alcohol intake has been associated with some risk. It is best to avoid alcohol. If you do consume alcohol, it should be limited to no more than 2 drinks a day for men and 1 drink a day for women.
Non-modifiable Risk Factors of Colorectal Cancer
Age: The risk of colorectal cancer increases as you age and is much more common after age 50. However, colorectal cancers have been on the rise in people under 55. In 2019, 20% of colorectal cancers were found in people less than 55. That was up from 11% in 1995. Therefore, colorectal cancer screenings begin at age 45 with a colonoscopy to detect polyps and colon or rectal cancer earlier.
Racial and Ethnic Background: Black Americans, American Indian, and Alaska Native peoples have the highest rates of colorectal cancer in the United States.
Sex: Men have a higher rate of CRC cancer than women.
Personal History of Colorectal Polyps or Colorectal Cancer: If you’ve had precancerous colon polyps in the past, you’re at an increased risk of developing colorectal cancer. This is especially true if the polyps are large, there are many of them, or if any of them show dysplasia. Dysplasia means the cells look abnormal, but they haven’t yet become cancer. Colorectal cancer can also come back even if it was completely removed in the past. You’re more likely to develop new cancers in other parts of the colon and rectum if you had your first colorectal cancer when you were younger.
Family History of Colorectal Cancer: When we talk about family history, we are talking about grandparents, parents, siblings, and children - those closest to you genetically. Colon or rectal cancer in any of these family members increases your chances of developing it too. Screening for colorectal cancer should begin at age 45, or ten years prior to your family member’s diagnosis, whichever comes first. Knowing this information can help you monitor your health and have regular screenings, which can help doctors find and remove precancerous polyps.
Inflammatory Bowel Disease (IBD): If you have either ulcerative colitis or Crohn’s disease, your risk of colorectal cancer is increased due to the long-term inflammation that can be present in these conditions. As a result, earlier and more frequent colonoscopies may be necessary for individuals with these conditions.
Other Non-modifiable Risk Factors: Cholecystectomy, previous radiation to the abdomen or pelvis, certain inherited syndromes, such as Lynch syndrome, familial adenomatous polyposis, Peutz-Jeghers syndrome, MUTYH-associated polyposis, cystic fibrosis.
What are Colon Polyps?
Polyps are very common, especially as you get older. Most polyps are benign, or noncancerous. However, some types of polyps can change into cancer over time, often over many years. Some types of polyps are more likely to turn into cancer. Other factors that can make a polyp more likely to lead to cancer include large size, large number of polyps, and dysplasia. Dysplasia refers to the abnormal appearance of cells, although they have not yet become cancerous.
Adenomatous polyps (adenomas): Adenomas are precancerous growths in the colon and rectum that have the potential to turn into cancer. There are three types of adenomas: tubular, villous, and tubulovillous. Tubular adenomas are the most common type and are usually small and round. Villous adenomas are the least common type but have a higher risk of becoming cancerous. Tubulovillous adenomas have features of both tubular and villous adenomas. All types of adenomas can vary in size and shape. While they are not yet cancer, they should be removed to prevent cancer from developing.
Hyperplastic polyps and inflammatory polyps: These polyps are more common than adenomatous polyps, and in general, they are not precancerous. However, some people with large hyperplastic polyps (more than 1 cm) might need more frequent colorectal cancer screening with colonoscopy. It is important to note that while these polyps are not cancerous, they can still cause symptoms such as bleeding, abdominal pain, and changes in bowel habits. If you have any of these symptoms, it is important to see your doctor for further evaluation.
Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA): These polyps are often treated like adenomas because they have a higher risk of changing into cancer.
Common Signs and Symptoms of Colorectal Cancer
The majority of patients with early-stage colon cancer experience no symptoms and these individuals are diagnosed as a result of screening. However, most colorectal cancers are diagnosed after the onset of symptoms. These symptoms are usually related to the growth of the cancer tumor into the lumen or nearby structures. Therefore, at the time of diagnosis, the cancer could be relatively advanced.
Typical symptoms of colorectal cancer include:
Change in bowel habits
Rectal bleeding
Abdominal pain
Unexplained iron deficiency anemia
Rectal pain, the feeling of incomplete emptying of stool, and diminished caliber of stool are associated with rectal cancer
Poor appetite and weight loss are general symptoms associated with various cancers
While colorectal cancer screening typically begins at age 45 (or younger with a family history of colorectal cancer), these concerning symptoms should be discussed with your Gastroenterologist and you may need a diagnostic colonoscopy despite your age or when your last colonoscopy was.
