When should colonoscopy screening begin for average‑risk adults and for high‑risk individuals such as those with a first‑degree relative with colorectal cancer or inflammatory bowel disease?

Colonoscopy Screening Start Age

For average-risk adults, begin colorectal cancer screening at age 45, with colonoscopy every 10 years or annual FIT as first-tier options; for high-risk individuals with a first-degree relative diagnosed before age 60 or two affected first-degree relatives at any age, start colonoscopy at age 40 or 10 years before the youngest affected relative's diagnosis age, whichever comes first. 1

Average-Risk Population

The U.S. Multi-Society Task Force on Colorectal Cancer updated their recommendations to lower the screening age from 50 to 45 years, though the strength of this recommendation varies by prior screening status 1:

• Ages 45-49: Clinicians should offer CRC screening to all average-risk individuals (weak recommendation, low-quality evidence) 1
• Age 50 and older without prior screening: Strong recommendation with high-quality evidence to begin screening 1

The rationale for lowering the age stems from rising colorectal cancer incidence in younger Americans, with observational data showing detection rates of advanced neoplasia in 45-49 year-olds at least as high as those aged 50-54 2. International data from Taiwan demonstrated a 22% reduction in CRC incidence and 39% reduction in mortality from screening those aged 40-49 2.

Screening Modalities for Average-Risk

First-tier options (recommended as cornerstones) 1:

• Colonoscopy every 10 years
• Annual fecal immunochemical test (FIT)

Second-tier options (appropriate when first-tier declined) 1:

• CT colonography every 5 years
• FIT-fecal DNA every 3 years
• Flexible sigmoidoscopy every 5-10 years

High-Risk Individuals

Family History of Colorectal Cancer

Begin colonoscopy at age 40 or 10 years before the age of diagnosis of the youngest affected relative, whichever comes first, in the following scenarios 3, 4:

• One first-degree relative with CRC or advanced adenoma diagnosed before age 60
• Two or more first-degree relatives with CRC or advanced adenoma diagnosed at any age

Screening interval: Every 5 years with colonoscopy 4

For individuals with a single first-degree relative diagnosed at age 60 or older, average-risk screening options can be offered beginning at age 40 4.

Inflammatory Bowel Disease

For patients with ulcerative colitis or Crohn disease with colonic involvement 3:

• Begin colonoscopy 8-10 years after symptom onset
• Repeat every 1-3 years depending on disease activity and other risk factors

Hereditary Syndromes

Hereditary Nonpolyposis Colorectal Cancer (Lynch Syndrome) 3:

• Begin colonoscopy at age 25
• Repeat every 1-2 years

Familial Adenomatous Polyposis 3:

• Begin screening at age 10-12
• Repeat every 1-2 years

Peutz-Jeghers Syndrome 3:

• Begin colonoscopy at age 8
• If normal, repeat at age 18, then every 3 years

Sessile Serrated Adenomatous Polyposis 3:

• Begin annual colonoscopy as soon as diagnosis is established

Critical Caveats

Resource considerations: Lowering the screening age requires adequate colonoscopy capacity and equitable access 1. Rising CRC incidence in younger populations must be balanced against potential increased wait times for diagnostic procedures in symptomatic individuals 2.

African Americans: Limited evidence supports beginning screening at age 45 in this population, though the 2022 guidelines now recommend age 45 for all average-risk individuals 4, 1.

Stopping age: Consider discontinuing screening at age 75 in individuals up-to-date with prior negative screening (particularly colonoscopy), or when life expectancy is less than 10 years 1. However, those without prior screening should be considered for screening up to age 85 depending on comorbidities 1.