|  | Cancer | Colon Cancer

Colorectal Cancer Symptoms, Risk Factors, and Screening Guidelines

Recognizing Red-Flag Symptoms

Colorectal cancer (CRC) often develops silently, but these signs warrant prompt evaluation:

  • Change in bowel habits (diarrhea, constipation, narrowing) >2 weeks
  • Rectal bleeding or blood in stool (bright red or dark/tarry)
  • Persistent abdominal pain, cramping, or bloating
  • Unexplained weight loss
  • Fatigue, weakness (may indicate anemia)
  • Nausea/vomiting (if obstruction)
  • Feeling of incomplete evacuation (tenesmus)

Key: Early-stage CRC has 90% 5-year survival; metastatic 14%. Symptom-to-diagnosis interval is critical.

Risk Factors

ModifiableNon-Modifiable
Obesity (BMI ≥30) Age ≥45 (median dx 66)
Physical inactivity Personal history: adenomas, CRC, IBD (UC/Crohn's)
Diet: high red/processed meat, low fiber Family history: 1st-degree relative with CRC/advanced adenoma
Alcohol (>2 drinks/day men, >1 women) Genetic syndromes: Lynch (HNPCC), FAP, MAP, etc.
Smoking Race/ethnicity: Black Americans highest incidence/mortality
Type 2 diabetes Prior abdominal/pelvic radiation

Screening Recommendations (USPSTF, ACS, Multi-Society)

  • Average risk: start at 45 (Grade A). Options:
    • Colonoscopy q10 yr (gold standard; diagnostic + therapeutic)
    • FIT annually (high sensitivity for cancer)
    • FIT-DNA (Cologuard) q3 yr
    • CT colonography q5 yr
    • Flexible sigmoidoscopy q5–10 yr + FIT
  • Increased risk (family history, personal history, IBD, genetic syndrome): earlier start (40 or 10 yr before youngest case), shorter intervals, colonoscopy preferred.
  • 76–85: individualized (C grade).

Diagnostic Workup for Symptoms

  • Colonoscopy (preferred; allows biopsy/polypectomy)
  • CT colonography if incomplete colonoscopy
  • Biopsy confirms diagnosis; staging with CT chest/abdomen/pelvis, MRI rectum, CEA.

Lifestyle Modification for Risk Reduction

  • Mediterranean/high-fiber diet (≥25–30 g fiber/day)
  • 150 min moderate activity/week
  • Weight management
  • Limit alcohol, quit smoking
  • Aspirin 81 mg/day for certain 50–59 yr (USPSTF B grade; discuss bleeding risk)

Call to Action

If you're ≥45 or have risk factors, schedule screening. If you have symptoms, don't wait for screening age—see a clinician now. CRC is preventable and curable when caught early.

Colon Cancer - Related Articles