screening and its reflection on CRC incidence rates.9, 45 Notably, however, declines in CRC incidence have decelerated in the most recent 5 data years (2012-2016), perhaps reflecting a slowing in firsttime screening,46 changing risk factors exposures, such as obesity, or a combination thereof. Age-specific incidence trends CRC trends overall reflect the majority of cases that occur in older age groups, masking trends in young adults. CRC incidence rates have been increasing since the mid-1980s in adults ages 20-39 years and since the mid-1990s in adults ages 40-54 years, with younger age groups experiencing the steepest increase.17 This pattern is called a birth cohort effect because generations of individuals with higher incidence carry the elevated risk with them as they age. Indeed, after decades of decline, incidence rates have also begun to increase in ages 50-64 years. During the most recent five data years (2012-2016), incidence rates increased by 2.2% annually in individuals younger than 50 years and by 1% annually in those ages 50-64 years, a sharp contrast to declines of 3.3% per year in adults ages 65 and older (Figure 7). Although a similar incidence pattern Rates are age adjusted to the 2000 US standard population. Incidence rates are adjusted for delays in reporting and exclude appendix. Due to changes in International Classification of Diseases (ICD) coding, numerator information for mortality has changed over time. Source: Incidence – Surveillance, Epidemiology, and End Results (SEER) Program, 2019. Mortality – US Mortality Volumes 1930 to 1959, US; Mortality Data 1960-2017, NCHS, 2019. © 2020, American Cancer Society, Inc., Surveillance Research Rate per 100,000 population Figure 6. Trends in Colorectal Cancer Incidence (1975-2016) and Mortality (1930-2017) Rates by Sex, US Female mortality Female incidence Male incidence 0 10 20 30 40 50 60 70 80 90 1930 1940 1950 1960 1970 1980 1990 2000 2010 Male mortality Year of diagnosis/death Colorectal Cancer Facts & Figures 2020-2022 7 has been reported in many other high-income countries,47 reasons for the increasing trend in younger age groups are unknown. It may reflect changes in established risk factors, such as a more sedentary lifestyle and/or unfavorable dietary patterns, or other exposures whose association with CRC risk is yet unknown. Rates are age adjusted to the 2000 US standard population. Incidence rates are adjusted for reporting delays and exclude appendix. Source: Incidence – NAACCR, 2019. Mortality – NCHS, 2019. ©2020, American Cancer Society, Inc., Surveillance Research Rate per 100,000 population Figure 7. Trends in Colorectal Cancer Incidence (1995-2016) and Mortality (1970-2017) Rates by Age and Sex, US Ages 0-49 Incidence Mortality Rate per 100,000 population Ages 50-64 Rate per 100,000 population Ages 65+ Male Female Male Female Rate per 100,000 population 2005 2010 2015 Male Female Female Male Female Year of diagnosis Year of death 8 Colorectal Cancer Facts & Figures 2020-2022 Racial/ethnic incidence trends Historical cancer incidence data in the US are available only for the categories white, black, and other race. CRC incidence was similar in whites and blacks until the mid-1980s, when rates began declining in whites while remaining stable in blacks (Figure 8). These trends created a widening racial gap until the mid-2000s and likely reflect a combination of earlier access to and more rapid uptake of CRC screening tests among whites, as well as changing patterns in the prevalence of CRC risk factors.48 Since the mid-2000s, CRC incidence rates decreased by about 1%-3% per year in all broadly defined racial/ethnic groups, although the pace appears to be slowing in recent years.24 Notably, the steepest increase in early-onset CRC is among NHWs and AIANs.49 As a result, incidence rates in NHWs ages 20-49 years are now equivalent to those in blacks (14.1 per 100,000 during 2015-2016), despite being 40% higher in blacks during 1995-1996. 50 Mortality CRC death rates have been decreasing since 1947 in women, but only since 1980 in men (Figure 6). This inconsistency likely reflects sex differences in incidence trends because of variable patterns in CRC risk factors,