Family history of colorectal cancer and prevalence of advanced colorectal neoplasia in asymptomatic screened populations in different age groups.

Background And Aims: The clinical significance of a family history (FH) of colorectal cancer (CRC) in first-degree relatives (FDRs) in CRC screening stratified by different age groups of screened individuals is not fully understood. We investigated the relationship between FH and the presence of advanced colorectal neoplasia (ACN) in screened individuals in different age groups.

Methods: Data from screened individuals aged 40 to 54 years (n = 2263) and 55 to 69 years (n = 2621) who underwent their first-ever screening colonoscopy were analyzed. The relationship between FH and ACN was examined, and a multivariate logistic regression analysis incorporating other baseline characteristics was performed.

Results: Among individuals aged 40 to 54 years, the prevalence of ACN was significantly higher in 249 individuals with affected FDRs than in those without (5.6% vs 1.6%; P < .01), with an adjusted odds ratio of 3.7 (95% confidence interval, 1.9-7.0; P < .01); the prevalence was particularly high in those having FDRs with CRC mortality (7.3%). Among individuals aged 55 to 69 years, the prevalence of ACN was not significantly different between 291 individuals with affected FDRs and those without (5.8% vs 5.8%; P = .95); however, individuals with 2 FDRs with CRC and mortality showed a high prevalence of ACN (17.4% and 42.9%, respectively).

Conclusions: An FH of CRC in FDRs was associated with a higher prevalence of ACN in younger individuals, with a particularly high impact of FH of CRC mortality. In contrast, the impact of FH was weaker in older individuals except those having 2 FDRs with CRC or mortality.