Colon Cancer Screening Starts at 45: What to Know

Turning 45 now comes with a new health milestone. For many adults in the United States, that’s the age when colorectal cancer screening should begin.

Yet confusion is common. Some people remember being told 50. Others have heard that screening may start earlier. And those with a family history often wonder if they are already behind.

Understanding the right colorectal cancer screening age can feel overwhelming—but it doesn’t have to be. Clear guidance from major U.S. medical organizations makes the path forward much simpler.

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Why Colorectal Cancer Screening Age Matters

Colorectal cancer is one of the most common cancers in the United States. It often develops slowly, beginning as small growths called polyps in the colon or rectum. These polyps may not cause symptoms at first.

Screening matters because it can:

Detect cancer early, when treatment is most effective
Find and remove precancerous polyps before they turn into cancer
Reduce the risk of dying from colorectal cancer

The key is starting at the right time—neither too late nor unnecessarily early for those at average risk.

What Is the Recommended Colorectal Cancer Screening Age?

Adults at Average Risk

According to the U.S. Preventive Services Task Force (USPSTF), the American Cancer Society (ACS), and the American College of Gastroenterology (ACG), the recommended colorectal cancer screening age for adults at average risk is:

Start at age 45.

“Average risk” means:

No personal history of colorectal cancer or certain types of polyps
No inflammatory bowel disease
No known hereditary cancer syndrome
No strong family history of colorectal cancer

Screening is recommended routinely from ages 45 to 75.

Adults Ages 76 to 85

For adults between 76 and 85, screening decisions are individualized.

Factors that may influence the decision include:

Overall health
Life expectancy
Whether screening was done previously
Personal values and preferences

For many healthy older adults who have never been screened, testing may still offer benefit. For others with significant medical conditions, the risks of screening may outweigh the benefits.

Who Should Start Colon Cancer Screening Before 45?

The general colorectal cancer screening age of 45 does not apply to everyone. Some individuals need to start earlier.

Family History of Colon Cancer

A family history of colon cancer changes the equation.

If a first-degree relative (parent, sibling, or child) was diagnosed with colorectal cancer or advanced polyps—especially before age 60—screening often begins:

At age 40, or
10 years before the youngest diagnosis in the family, whichever comes first

This is one of the most common reasons for earlier screening.

Inflammatory Bowel Disease

People with ulcerative colitis or Crohn’s disease affecting the colon have a higher long-term risk of colorectal cancer.

Screening in these cases usually starts earlier and may be performed more frequently, depending on how long the disease has been present.

Hereditary Cancer Syndromes

Certain inherited conditions significantly raise cancer risk, including:

Lynch syndrome
Familial adenomatous polyposis (FAP)

In these cases, screening may begin in the 20s or even earlier, depending on the condition. Specialized care and genetic counseling are typically recommended.

If there is uncertainty about risk level, discussing personal and family history with a primary care clinician can clarify the appropriate colorectal cancer screening age.

What Are the Main Colonoscopy Age Recommendations and Test Options?

When discussing when to start colon cancer screening, the next question is often: which test?

Several options are considered effective. The “best” test is usually the one that gets done consistently.

Colonoscopy

Typically done every 10 years if results are normal
Allows direct visualization of the entire colon
Enables removal of polyps during the same procedure

Colonoscopy remains a widely used option and is often recommended for individuals at higher risk.

Stool-Based Tests

These are noninvasive and done at home:

FIT (fecal immunochemical test): every year
Stool DNA test (such as Cologuard): every 1–3 years

If abnormal, a follow-up colonoscopy is required.

Other Visual Tests

CT colonography (virtual colonoscopy) every 5 years
Flexible sigmoidoscopy (less commonly used now)

Each option has advantages and limitations. A conversation with a healthcare professional can help match the test to personal preferences, medical history, and access.

Why Did the Recommended Screening Age Change?

For years, 50 was considered the standard colorectal cancer screening age.

However, research over the past decade has shown a concerning rise in colorectal cancer among adults younger than 50. While overall rates in older adults have declined—largely due to screening—cases in younger populations have increased.

Modeling studies reviewed by the USPSTF found that starting screening at 45 instead of 50 provides additional life-years gained with an acceptable balance of benefits and risks.

As a result, in 2021 the USPSTF officially lowered the recommended starting age to 45. The American Cancer Society had already made this change in 2018.

This shift reflects evolving evidence—not alarmism. Most younger adults remain at relatively low risk. But beginning at 45 improves prevention at the population level.

What If You’re Not Sure About Your Risk?

Many adults are uncertain whether they fall into the “average risk” category.

Questions worth reviewing include:

Has anyone in the immediate family had colon cancer or advanced polyps?
At what age were they diagnosed?
Has there ever been genetic testing in the family?
Have there been symptoms such as unexplained bleeding, persistent abdominal pain, or changes in bowel habits?

Symptoms are not part of routine screening—but they do require medical evaluation, regardless of age.

When uncertainty exists, primary care clinicians can help determine the appropriate colorectal cancer screening age and testing schedule.

The Bottom Line on Colorectal Cancer Screening Age

For most adults in the United States, the recommended colorectal cancer screening age is 45.

From ages 45 to 75, screening is strongly recommended for those at average risk. After 75, decisions are individualized. And for individuals with a family history, inflammatory bowel disease, or hereditary syndromes, screening often starts earlier.

Colorectal cancer is one of the most preventable cancers when screening happens on time. Starting at the right age—and choosing a test that fits personal circumstances—can make a meaningful difference.

If age 45 is approaching, it may be time to put colorectal cancer screening on the preventive care checklist.

Medical Disclaimer: This content is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult your physician or a qualified healthcare provider with any questions about a medical condition.