Introduction: Colorectal cancer (CRC) is the second leading cause of cancer-related mortality in the United States (US). Previous reports have shown significant changes in the epidemiology of CRC. However, there is limited information regarding disparities in CRC incidence among various racial/ethnic groups. Our study aims to perform a race-, age- and sex-specific time trend analysis of CRC incidence rates from 2000 through 2019 using the Centers for Disease Control and Prevention’s (CDC) Wide-ranging Online Data for Epidemiologic Research (WONDER) database.

Method: Data were obtained from the CDC WONDER database, which includes ~100% of CRC diagnoses in the US. CRC incidence rates, age-adjusted to the year 2000 US census population, were calculated using SEER*Stat software (v. 5.0.2, “NCI”) and were stratified by gender and racial/ethnic group as reported in the database. Time trends were estimated as annual percentage change (APC) and average APC (AAPC) using Joinpoint Regression Software (v. 5.0.2, “NCI”) utilizing Monte Carlo permutation analysis to generate the simplest trend. A pairwise comparison was conducted between gender-specific trends using the tests of parallelism and coincidence. Age-specific trends were also assessed in two age sub-groups: younger adults (age <45 years) and older adults (age ≥45 years). A two-sided P-value cut-off of 0.05 was utilized for statistical significance.

Results: 2,927,574 cases of CRC (48.3% women) were reported. AAPC of the total CRC cases decreased among women (-2.3%; P< .001) and men (-2.6%; P< .001) with an absolute AAPC difference of 0.3% (P=0.01). For the past 20 years, CRC incidence has increased in individuals <45 years (AAPC=2.4%; P< .001). However, the trend reversed in those ≥45 years (AAPC= -2.7%; P< .001), with a large between-group difference (5.1%; P< .001). When stratified by different census regions, the Northeast had the highest decrease (AAPC= -2.9%; P< .001), compared to the South, which had the lowest decrease across the US (AAPC= -2.1%; P< .001). White race individuals aged <45 years (AAPC=2.8%; P< .001) had the highest increase in incidence, while those aged ≥45 years had the greatest decrease (AAPC= -2.7%; P< .001) in incidence across all racial/ethnic groups. The lowest increase in incidence rates was observed in Black race individuals aged <45 years (AAPC= 0.9%; P< .001). American Indians aged ≥45 years had the lowest decrease in incidence across all groups (AAPC= -1.5%; P< .001).

Conclusion: Our analysis suggests that despite efforts to improve CRC screening, there continue to be significant racial disparities in CRC incidence trends over the last two decades. While the overall CRC rates declined, the decrease in CRC incidence was lowest in American Indians across all age groups. This suggests the need for targeted interventions to improve CRC screening in minority populations.

<b>Table: </b>CRC incidence rates trend analysis according to age, gender, racial/ethnic group, and geographical region.

Table: CRC incidence rates trend analysis according to age, gender, racial/ethnic group, and geographical region.

<b>Figure:</b> CRC incidence rates trend analysis according to age, gender, racial/ethnic group, and geographical region.

Figure: CRC incidence rates trend analysis according to age, gender, racial/ethnic group, and geographical region.

Leen Rawabdeh

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