At what age should colonoscopy (colon examination) screening start in individuals with a family history of colorectal cancer?

From the Guidelines

Individuals with a family history of colorectal cancer should typically begin colonoscopy screening at age 40, or 10 years before the age at which their youngest affected relative was diagnosed, whichever comes first. This recommendation is based on the most recent and highest quality study, which suggests that having a first-degree relative (parent, sibling, or child) with colorectal cancer approximately doubles the risk of developing the disease 1. The risk increases further with multiple affected relatives or relatives diagnosed at a young age.

Some key points to consider when determining the appropriate age to start colonoscopy screening in individuals with a family history of colorectal cancer include:

• If a first-degree relative was diagnosed with colorectal cancer at age 45, screening should start at age 35
• The screening frequency is generally every 5 years for those with a family history, compared to every 10 years for average-risk individuals
• Certain hereditary syndromes like Lynch syndrome or familial adenomatous polyposis may require even earlier or more intensive screening protocols
• The purpose of colonoscopy is to detect and remove precancerous polyps before they develop into cancer, or to find cancer at an early, more treatable stage

It's essential to discuss specific family history with a healthcare provider to determine the best course of action, as the risk of colorectal cancer can vary significantly depending on the individual's family history and other factors 1.

From the Research

Colonoscopy Screening Guidelines for Individuals with a Family History of Colorectal Cancer

• The age to start colonoscopy screening for individuals with a family history of colorectal cancer varies depending on the degree and age of relatives diagnosed with colorectal cancer or adenomatous polyps 2, 3, 4.
• Individuals with one first-degree relative (FDR) with colorectal cancer or an advanced adenoma diagnosed at any age are recommended to undergo colonoscopy every 5 to 10 years starting at age 40 to 50 years or 10 years younger than the age at diagnosis of the FDR 2.
• Those with a FDR diagnosed with colorectal cancer or adenomatous polyps before 60 years of age or multiple FDRs diagnosed at any age should begin screening with colonoscopy at 40 years of age or 10 years younger than the earliest affected relative and undergo a repeat colonoscopy every 5 years 3, 4.
• Individuals with a family history of non-advanced adenomas or a history of colorectal cancer in second-degree relatives should be screened according to average-risk guidelines 2.
• A nurse-led tailored intervention can be effective in promoting colonoscopy screening uptake among siblings of patients diagnosed with colorectal cancer or adenomatous polyps before age 60 years 5.

Special Considerations for High-Risk Individuals

• Individuals with a personal or family history of advanced adenomas or colorectal cancer, a personal history of inflammatory bowel disease, or genetic polyposis syndromes should undergo more frequent or earlier testing than individuals at average risk 4.
• Those with hereditary nonpolyposis colorectal cancer should begin colonoscopy at 25 years of age and repeat colonoscopy every one to two years 4.
• Individuals with adenomatous polyposis syndromes should begin screening at 10 years of age or in their mid-20s, depending on the syndrome, and repeat colonoscopy typically every one to two years 4.
• Genetic testing is necessary to distinguish among inherited colorectal cancer conditions, such as Lynch syndrome, familial adenomatous polyposis, and MYH-associated polyposis 6.