The key factors known to increase the risk of colorectal (colon and rectal) cancer

Here is a detailed overview of the key factors known to increase the risk of colorectal (colon and rectal) cancer, categorized for clarity.

Major Risk Factors (Non-Modifiable)

These are factors you cannot change. Knowing them helps determine when you should start screening.

1. Age: The single largest risk factor. The vast majority of cases are diagnosed in people over 50. However, incidence is rising in younger adults.

2. Personal History:

   • Previous colorectal cancer or certain types of polyps (adenomas).

   • Inflammatory Bowel Disease (IBD): Chronic conditions like ulcerative colitis and Crohn’s disease significantly increase risk.

3. Family History & Genetics:

   • Close relatives (parent, sibling, child) diagnosed with colorectal cancer, especially before age 50.

   • Inherited Genetic Syndromes: Account for about 5-10% of cases.

     • Lynch Syndrome (HNPCC): The most common hereditary form.

     • Familial Adenomatous Polyposis (FAP): Causes hundreds of polyps at a young age.

   • Family history of certain other cancers (endometrial, ovarian, stomach).

4. Race and Ethnicity: African Americans have the highest incidence and mortality rates in the U.S. Ashkenazi Jews also have a higher risk.

Lifestyle & Dietary Risk Factors (Modifiable)

These are factors you can influence to lower your risk.

1. Diet:

   • Low Fiber, High Fat Diet: Diets low in fruits, vegetables, and whole grains.

   • High Consumption of Red and Processed Meats: Beef, pork, lamb, hot dogs, bacon, and sausages are strongly linked to increased risk.

   • Low Calcium and Vitamin D.

2. Physical Inactivity: A sedentary lifestyle increases risk.

3. Obesity: Being overweight or obese, particularly with excess abdominal fat, increases the risk of developing and dying from colorectal cancer.

4. Smoking: Long-term smokers are at higher risk than non-smokers.

5. Heavy Alcohol Consumption: Regular, heavy drinking (more than 3 drinks per day for men, 2 for women) is a clear risk factor.

6. Type 2 Diabetes: People with type 2 diabetes (often linked to insulin resistance and obesity) have an increased risk.

Other Medical Conditions & Exposures

1. Radiation Therapy: Previous radiation directed at the abdomen for other cancers (e.g., prostate, cervical).

2. Gut Microbiome: An imbalance in gut bacteria (dysbiosis) is an area of active research and may play a role.

Key Takeaways for Prevention & Early Detection

• Screening is Paramount: Most colorectal cancers start as benign polyps. Screening tests (colonoscopy, stool-based tests) can find and remove polyps before they become cancer. This is the most powerful tool to prevent death from this disease.

  • General guideline: Start at age 45 (lowered from 50 due to rising rates in younger people).

  • Earlier screening: If you have a family history or other risk factors, talk to your doctor about starting 10 years before the age your youngest relative was diagnosed.

• Adopt a Protective Lifestyle:

  • Eat: A diet rich in fruits, vegetables, and whole grains. Limit red and processed meats.

  • Exercise: Get regular physical activity.

  • Maintain a healthy weight.

  • Avoid smoking and limit alcohol.

• Know the Symptoms: Don’t ignore changes like:

  • Persistent change in bowel habits (diarrhea, constipation, narrowing of stool).

  • Rectal bleeding or blood in the stool.

  • Persistent abdominal discomfort (cramps, gas, pain).

  • Feeling that your bowel doesn’t empty completely.

  • Unexplained weakness, fatigue, or weight loss.

If you have concerns about your personal risk, the most important step is to have a conversation with your doctor to develop a personalized screening and prevention plan.