Colorectal Cancer: Early Warning Signs, Risk Factors, and Prevention Strategies

Colorectal cancer (CRC) is the third leading cause of cancer mortality in the United States. Early detection through symptom recognition and screening dramatically improves survival—5-year relative survival is 91% for localized disease vs. 14% for distant metastases.

Eight Warning Signs Requiring Evaluation

1. Persistent bowel habit change: Diarrhea, constipation, or caliber change >2 weeks.
2. Rectal bleeding or hematochezia: Bright red or dark blood; never assume hemorrhoids without evaluation.
3. Abdominal discomfort: Cramping, bloating, gas pains, or persistent ache.
4. Unexplained weight loss: >5% body weight in 6–12 months without dietary change.
5. Fatigue disproportionate to activity: May reflect chronic blood loss anemia.
6. Iron deficiency anemia: Especially in men and postmenopausal women—mandates GI evaluation.
7. Narrow (pencil-thin) stools: Suggests luminal narrowing from circumferential lesion.
8. Tenesmus: Persistent urge to defecate with minimal output.

Risk Stratification

• Average risk: Screening at age 45 (USPSTF/ACS); colonoscopy q10y, FIT annually, Cologuard q3y, CT colonography q5y.
• Increased risk: Family history (1st-degree relative <60y or 2 relatives any age), personal history of polyps/CRC, IBD, hereditary syndromes (Lynch, FAP) → earlier, more intensive surveillance.

Primary Prevention

• Diet: High fiber (fruits, vegetables, whole grains); limit red/processed meat.
• Physical activity: ≥150 min/week moderate intensity.
• Weight management: Avoid obesity (BMI ≥30).
• Avoid tobacco; limit alcohol (≤1 drink/day women, ≤2 men).
• Consider low-dose aspirin (50–59y, CVD risk ≥10%) per USPSTF shared decision-making.

Early diagnosis saves lives. Do not ignore symptoms because of age or embarrassment.