Colon Age: A Metric for Whether and How to Screen Male Veterans for Early-Onset Colorectal Cancer.

We aimed to develop a metric for estimating risk for early-onset colorectal cancer (EOCRC) to help decide whether and how to screen persons < age 50. We used risk prediction models derived and validated on male veterans to calculate the RRs for six scenarios: one low-risk scenario (no risk factors present), four intermediate risk scenarios (some risk factors present), and one high-risk scenario (all risk factors present) for three age groups (35-39, 40-44, and 45-49 years). For each scenario, we estimated absolute colorectal cancer risk using Surveillance Epidemiology and End Results colorectal cancer incidence rates and each scenario's RR. We identified the current Surveillance Epidemiology and End Results 5-year age group to which the revised estimate was closest and refer to the midpoint of this group as the "colon age." When the revised estimate equals or exceeds that for 50- to 54-year-olds and for 70- to 74-year-olds, respective recommendations were made for (any) colorectal cancer screening and screening with colonoscopy. Among the scenarios, there was inconsistency between the two models for the 35 to 39 and 40 to 44 age groups, with only the 15-variable model recommending screening for the higher-risk 35- to 39-year-olds. Both models recommended screening for some intermediate risk and high-risk 40- to 44-year-olds. The models were well aligned on whether and how to screen most 45- to 49-year-olds. Using risk factors for EOCRC with colorectal cancer incidence rates, "colon age" may be useful for shared decision-making about whether and how to screen male veterans <50 years. For 45- to 49-year-olds, the 7-variable model may be preferred by patients, providers, and health systems. Prevention Relevance: A new metric known as "colon age" expresses risk of EOCRC based on biological risk and may be useful for providers to explain and for patients to understand colorectal cancer risk when considering whether and how to be screened for colorectal cancer prior to age 45 or 50.