What is the recommended screening method for colon cancer?

Colon Cancer Screening

For average-risk adults, begin screening at age 50 with either colonoscopy every 10 years or annual fecal immunochemical testing (FIT) as first-tier options, and continue screening until age 75. 1

Screening Age and Population

Average-Risk Individuals

• Start screening at age 50 years for the general population with strong evidence supporting substantial mortality reduction 1
• African Americans should begin screening at age 45 years due to higher incidence and earlier onset of colorectal cancer, though this is based on weaker evidence 1
• Continue screening until age 75 years in individuals who are up-to-date with prior negative screening tests 1

When to Stop Screening

• Ages 76-85 years: Individualize the decision based on life expectancy, comorbidities, and prior screening history—routine screening is not recommended, but may be considered in select patients who have never been screened 1
• Age 85 and older: Do not screen, as harms outweigh benefits 1
• Discontinue screening when life expectancy is less than 10 years, particularly in patients with negative prior colonoscopy 1

First-Tier Screening Methods (Choose One)

The U.S. Multi-Society Task Force ranks screening tests in tiers, with colonoscopy and FIT as first-tier options that should be offered as cornerstones of any screening program 1, 2:

Colonoscopy Every 10 Years

• Most commonly used screening test in the United States, valued for its high sensitivity for precancerous lesions of all sizes 3, 4
• Allows direct visualization and simultaneous removal of polyps, providing both diagnostic and therapeutic capability 1
• Provides long-lasting protection with evidence supporting eventual 15-year intervals for patients with completely normal examinations 4
• Preferred in opportunistic screening settings and for patients who value comprehensive single-examination approach 1

Annual Fecal Immunochemical Testing (FIT)

• Non-invasive stool-based test that detects occult blood from colorectal lesions 1, 2
• Preferred in organized screening programs due to ease of distribution and completion 1
• Requires annual adherence to maintain effectiveness—a single negative test does not provide long-term protection 1
• Positive FIT results require follow-up colonoscopy for diagnostic evaluation 1

Second-Tier Screening Options

These tests are appropriate alternatives but have disadvantages relative to colonoscopy and FIT 1, 2:

• CT colonography every 5 years: Non-invasive imaging requiring bowel preparation; positive findings require colonoscopy 1
• FIT-DNA testing every 3 years: Combines FIT with stool DNA markers; more expensive and requires colonoscopy follow-up for positive results 1
• Flexible sigmoidoscopy every 5-10 years: Visualizes only the left colon; often combined with annual FIT to improve right colon detection 1

High-Risk Screening Modifications

Family History

• One first-degree relative with colorectal cancer or advanced adenoma diagnosed before age 60, OR two first-degree relatives at any age: Begin colonoscopy at age 40 or 10 years before the youngest affected relative's diagnosis (whichever is earlier), repeat every 5 years 1, 5
• Single first-degree relative diagnosed at age 60 or older: Offer average-risk screening options beginning at age 40 years 1

Inflammatory Bowel Disease

• Chronic ulcerative colitis or Crohn's disease: Colonoscopy every 1-2 years starting 8 years after onset of pancolitis or 12-15 years after onset of left-sided colitis 1

Hereditary Syndromes

• Familial adenomatous polyposis (FAP): Annual flexible sigmoidoscopy beginning at age 10-12 years with genetic counseling 1
• Hereditary nonpolyposis colorectal cancer (HNPCC/Lynch syndrome): Colonoscopy every 1-2 years beginning at age 20-25 years or 10 years before youngest affected family member 1

Symptomatic Patients Require Diagnostic Evaluation

• Patients under age 50 with colorectal bleeding symptoms (hematochezia, unexplained iron deficiency anemia, melena with negative upper endoscopy) require colonoscopy regardless of screening guidelines 1
• New-onset narrowed stools or other alarm symptoms necessitate urgent diagnostic colonoscopy within 30 days, not repeat stool testing, even with recent negative FIT 6
• FIT should never be used in symptomatic patients as it is a screening test for asymptomatic individuals and should not delay diagnostic evaluation 6

Practical Implementation Approach

Sequential Offer Strategy

Offer colonoscopy first; if declined, offer FIT; if both declined, offer second-tier tests 1. This approach results in higher colonoscopy uptake while maintaining overall screening adherence comparable to multiple-option approaches 1, 4.

Risk-Stratified Approach

Use colonoscopy for patients with higher pretest probability of neoplasia (family history, older age within screening range) and FIT for those with lower pretest probability 1.

Common Pitfalls to Avoid

• Do not use FIT in symptomatic patients—this delays necessary diagnostic colonoscopy and risks missing advanced disease 6
• Do not defer screening based solely on age in symptomatic patients—alarm symptoms require evaluation regardless of screening guidelines 6
• Do not assume a single negative FIT provides long-term protection—annual testing is required for effectiveness 1
• Do not continue routine screening beyond age 75 in patients up-to-date with negative prior tests—harms begin to outweigh benefits 1
• Ensure adequate bowel preparation for colonoscopy—poor preparation compromises detection and may require repeat examination 1, 6