269 Colorectal Cancer Annual Percent Change Incidence Analysis in 40–49 and 50–54 Year-Olds Utilizing 2000–2016 SEER 18 Data and Stratified by Histology

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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.