IMPORTANCE Early-onset colorectal cancer incidence rates among patients aged 45 to 49 years have been considered much lower compared with the rates among patients aged 50 to 54 years, prompting debate about earlier screening benefits at 45 years. However, the observed incidence rates in the Surveillance, Epidemiology, and End Results (SEER) registries may underestimate colorectal cancer case burdens in those younger than 50 years compared with those older than 50 years because average-risk screening is generally not performed to detect preclinical cases of colorectal cancer. Finding steep incidence increases of invasive stage (beyond in situ) cases of colorectal cancer from age 49 to 50 years would be consistent with high rates of preexisting, undetected cancers in younger patients ultimately receiving a diagnosis of colorectal cancer after undergoing screening at 50 years.OBJECTIVE To assess the preclinical burden of colorectal cancer by analyzing its incidence in 1-year age increments, focusing on the transition between ages 49 and 50 years. DESIGN, SETTING, AND PARTICIPANTSData from the SEER 18 registries, representing 28% of the US population, were used to conduct a cross-sectional study of colorectal cancer incidence rates from January 1, 2000, to December 31, 2015, in 1-year age increments (ages 30-60 years) stratified by US region (South, West, Northeast, and Midwest), sex, race, disease stage, and tumor location. Statistical analysis was conducted from November 1, 2018, to December 15, 2019. MAIN OUTCOMES AND MEASURES Incidence rates of colorectal cancer. RESULTS A total of 170 434 cases of colorectal cancer were analyzed among 165 160 patients (92 247 men [55.9%]; mean [SD] age, 51.6 [6.7] years). Steep increases in the incidence of colorectal cancer in the SEER 18 registries were found from 49 to 50 years of age (46.1% increase: 34.9 [95% CI, 34.1-35.8] to 51.0 [95% CI, 50.0-52.1] per 100 000 population). Steep rate increases from 49 to 50 years of age were also seen in all US regions, men and women, white and black populations, and in colon and rectal cancers. The rate ratio incidence increase in the SEER 18 registries from 49 to 50 years of age (1.46 [95% CI, 1.42-1.51]) was significantly higher than earlier 1-year age transitions. Steep rate increases in the SEER 18 registries were found from 49 to 50 years of age in localized-stage (75.9% increase: 11.2 [95% CI, 10.7-11.7] to 19.7 [95% CI, 19.0-20.3] per 100 000) and regional-stage (30.3% increase: 13.2 [95% CI, 12.7-13.8] to 17.2 [95% CI, 16.7-17.8] per 100 000) colorectal cancers. A total of 8799 of the 9474 cases (92.9%) of colorectal cancer in the SEER 18 registries from 2000 to 2015 that were diagnosed among individuals aged 50 years were invasive. CONCLUSIONS AND RELEVANCE Steep incidence increases between 49 and 50 years of age are consistent with previously undetected colorectal cancers diagnosed via screening uptake at 50 years. These cancers are not reflected in observed rates of colorectal cancer in the SEER registries among individuals y...

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Background Although early‐onset colorectal cancer (EOCRC) incidence rates (IRs) are increasing, geographic and intra‐racial IR disparities are not well defined. Methods 2000‐2015 Surveillance, Epidemiology, and End Results (SEER) program CRC IR Analysis (170,434 cases) was performed from ages 30 to 60 in four US regions, 18 individual registries, metropolitan and nonmetropolitan locations and stratified by race. Analyses were conducted in 1‐year and 5‐year age increments. Results Wide US regional EOCRC IR variations exist: For example, age 45 IRs in the south are 26.8/100,000, 36.0% higher than the West, 19.7/100,000 ( p < 0.0001). Disparities magnify between individual registries: EOCRC IRs in highest risk registries were 177‐348% (Alaska Natives), 75‐200% (Hawaii), 76‐128% (Louisiana), and 61‐125% (Kentucky) higher than lowest risk registries depending on age. EOCRC IRs are 18.2%‐25.6% higher in nonmetropolitan versus metropolitan settings. Wide geographic intra‐racial disparities exist. Within the White population, the greatest IR difference (78.8%) was between Kentucky (5.9/100,000) and Los Angeles (3.3/100,000) in 30‐ to 34‐year‐olds ( p < .0001). Within the Black population, the greatest difference (136.2%) was between rural Georgia (30.7/100,000) and California excluding San Francisco‐Oakland/San Jose‐Monterey/Los Angeles (13/100,000) in 40‐ to 44‐year‐olds ( p = 0003). Conclusion Marked geographic EOCRC disparities exist with disproportionately high IRs in Alaska Natives, Hawaii, and southern registries. Geographic intra‐racial disparities are present within White and Black populations. In Blacks, there are disproportionately high EOCRC IRs in rural Georgia. Although vigilance is required in all populations, attention must be paid to these higher risk populations. Potential interventions include assuring early investigation of symptoms, targeting modifiable risk factors and utilizing earlier age 45 screening options supported by some guidelines.

INTRODUCTION: SEER 9 analysis has revealed rising early-onset colorectal cancer (EOCRC) incidence. We seek to analyze SEER 18 EOCRC rates as this represents a greater percentage of the U.S. population compared to SEER 9 (28% vs. 9%). Furthermore, given evidence carcinoid (CN) rates are increasing and these tumors may potentially be broadly categorized as “colorectal cancer,” we aimed to substratify analysis by histology. METHODS: Age-specific CRC, colon only and rectal only incidence rates from SEER 18 (2000–2016) were generated in yearly intervals using SEER*Stat. Age 20–29 and 30–39 blocks were analyzed and Joinpoint regression was used to calculate annual percent changes (APC). Histologic categories included all CRCs, adenocarcinomas (AC), CNs and CRCs without CNs. RESULTS: Age 20–29 overall CRC APC was 3.39% from 2001–2013 and 14.55% from 2013–2016. Colon AC APCs (1.03% from 2000–2016) and rectal AC APCs (7.42% 2000–2006, −0.24% 2007–2016) in 20–29 year-olds were not statistically significant. However, colorectal combined ACs had a statistically significant, modest APC of 1.12%. In contrast, 2007–2016 age 20–29 colon CN APC was 41.05%. Rectal CN APCs were not significantly changed. Age 30–39 overall CRC APCs were 1.58% from 2000–2010 and 4.03% from 2010–2016. Age 30–39 2000–2016 colorectal AC APCs were 1.89% with a colon AC APC of 1.59% and rectal AC APC of 2.40%. Age 30–39 colonic CN APCs were 32.81% from 2010–2016. Rectal CN APCs were 2.90% from 2000–2016. CONCLUSION: Age 20–29 overall CRC rate increases in SEER 18 appear to be driven in large part by increasing CN incidence. Although there was a significant colorectal AC APC of 1.12% in 20–29 year-olds, there was no significant APC increase in colon ACs. There appeared to be an increased APC trend in rectal ACs from 2000–2006 (7.42%), however this was non-significant and there was a negative trend from 2006–2016. In contrast, colon and rectal ACs in the 30–39 age group have been steadily increasing. In both age groups, colon CNs have been increasing faster than rectal CNs. Reasons are unclear but could potentially represent increased use of colonoscopy which can detect proximal lesions. Study limitations include underreported age 20–29 CN rates from 2000–2006. Overall, findings support rises in CRC incidence in young adults, however this is less from ACs in 20–29 year-olds. Despite these findings, ACs are still present in 20–29 year-olds and concerning symptoms should trigger diagnostic evaluations.

INTRODUCTION: Prior study by our group revealed marked geographic disparities in early-onset colorectal cancer (EOCRC) incidence rates (IR) (Abualkhair et al. abstract #984 DDW 2019). Although it is established CRC IRs in African Americans are higher than whites, there is paucity of data on geographic EOCRC disparities within both white and African American populations. Hence, we seek to explore the role race may play in IR differences between U.S. regions and individual registries. METHODS: 2000–2015 SEER 18 CRC IR Analysis (170,434 cases) was performed in one-year age increments (ages 30–60) in four U.S. regions, individual registries and stratified by race. RESULTS: There are wide regional IR disparities at multiple ages within both white and African American populations. For example, at age 45, there is a 52% difference (P < 0.05) between the highest (south) and lowest (west) regional IRs in African Americans compared to a 32% difference (P < 0.05) in whites (Figures 1 and 2). At multiple age points <50, there is a trend for greater disparity between the highest and lowest regional IRs within the African American population compared to within the white population (shaded boxes in Figure 2) however these did not reach statistical significance at most ages. CONCLUSION: There are marked geographic EOCRC IR disparities within white and African American populations between U.S. regions. There appears to be a trend toward more pronounced geographic disparities within the African American population, however interpretation is limited by lack of statistical significance at multiple age points, likely due to lower case counts. Targeting all populations is critical for CRC prevention, however we must assure attention is paid to higher-risk populations. Potential interventions include targeted risk factor modifications, assuring concerning symptoms trigger prompt diagnostic evaluations and taking advantage of earlier age 45 screening options supported by some guidelines (USMSTF recommends screening African Americans at age 45 and ACS recommends average-risk screening of all patients at age 45). By identifying higher-risk populations, future targeted studies can also be performed which may allow better understanding of rising EOCRC rates.

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INTRODUCTION: SEER 9 analysis has revealed rising incidence of early-onset colorectal cancer (EOCRC) in 40–49 year-olds and within 50–54 year-olds. We seek to analyze SEER 18 EOCRC rates as this represents a greater percentage of the U.S. population compared to SEER 9 (28% vs. 9%). Furthermore, given evidence carcinoid (CN) rates are increasing and these tumors may potentially be broadly categorized as “colorectal cancer,” we aimed to sub-stratify analysis by histology. METHODS: Age-specific CRC, colon only and rectal only incidence rates from SEER 18 (2000–2016) were generated in yearly intervals using SEER*Stat. Age 40–49 and 50–54 blocks were analyzed, and Joinpoint regression was used to calculate annual percent changes (APC). Histologic categories included all CRCs, adenocarcinomas (AC), CNs, and CRCs without CNs. RESULTS: Age 40–49 overall CRC APC was 1.45% from 2000–2016. Colon AC APC was 1.08% from 2000–2016, and rectal AC APC was 1.49% 2000–2016. Age 50–54 overall CRC APCs was 1.06% from 2000–2016. Age 50–54 2000–2016 CRC AC APCs was 0.55% with a colon AC APC of 0.27% and rectal AC APC of 1.09%. Age 40–49 CRC CN APC was 4.58% from 2000–2016. Age 50–54 CRC CN APCs were 10.35% from 2000–2008, −1.09% from 2008–2012, and 9.41% from 2012–2016. All results were statistically significant except Age 50–54 colon AC APC 2000–2016 (0.27%) and Age 50–54 CRC CN APC 2008–2012 (−1.09%). CONCLUSION: Age 40–49 and 50–54 overall CRC rate increases in SEER 18 appear to be driven by all histology sub-types, including AC and CN. Although there was significant increase in colorectal AC APC of 0.55% in 50–54 year-olds, there was no significant APC increase in colon ACs, but significant increase in rectal ACs. In both age groups, colon and rectal CNs incidences have been increasing faster than ACs. Importantly, rising CN incidence is significantly factoring into the increase in CRC in ages 40–49 and 50–54. Reasons are unclear but could potentially represent increased use of colonoscopy which can detect proximal lesions. Overall, findings support rises in CRC incidence in EOCRC and ages 50–54. Despite these findings, ACs are still rising in 40–54 year-olds, and concerning symptoms should trigger diagnostic evaluations.