Tulane University School of Medicine New Orleans, LA, United States
Eric M. Montminy, MD1, Meijiao Zhou, PhD, MPH2, Lauren Maniscalco, MPH3, Harrison Penrose, PhD1, Swati Patel, MD4, Xiao-Cheng Wu, MD, MPH3, Jordan J. Karlitz, MD, FACG5 1Tulane University School of Medicine, New Orleans, LA; 2Fresenius Medical North America, Waltham, MA; 3Louisiana State University Health Sciences Center; Louisiana Tumor Registry, New Orleans, LA; 4University of Colorado School of Medicine, Denver, CO; 5Denver Health and Hospital, Denver, CO
Introduction: Early-onset colorectal cancer (EOCRC) incidence rates (IRs) are increasing. Given screening controversies at age 45 vs. 50, our study performs a race stratified CRC IR analysis of 40-49-year-olds. We focused on adenocarcinomas due to recent evidence of carcinoids significantly impacting EOCRC IRs reporting. We utilized the SEER 18 database, which has expanded race data compared to prior studies.
Methods: 2000-2017 SEER 18 annual age-adjusted CRC IRs stratified by anatomic subsite (colon vs. rectum), adenocarcinoma, and race (non-Hispanic white/non-Hispanic black) were acquired from SEER*Stat (version 8.3.6 [NCI]). Joinpoint Regression quantified yearly annual percent change (APC) in IRs/100,000 person-years for subgroups. Annual IR rate ratios between subgroups were calculated and significant differences were determined when rate ratio confidence intervals (at 95%) did not overlap.
Results: Age 40-49 white colorectal adenocarcinoma IRs increased from 19.6/100,000 in 2000 to 25.2/100,000 in 2017 (APC 1.6, CI 1.3↔1.9, p< 0.05) (figure 1a). Black adenocarcinoma IRs were stable: 26.4/100,000 in 2000 and 25.8/100,000 in 2017 (APC -0.03, CI -0.5↔0.5, p >0.05). There were no significant differences in annual rate ratios between white and black colorectal adenocarcinoma IRs from 2014-2017 (p >0.05).
White and black rectal-only adenocarcinoma IRs remained similar from 2000-2008 but diverged in 2009 (significant rate ratio differences) with white rectal adenocarcinoma absolute IRs becoming significantly higher and with significant IR increases (APC 2.2, CI 1.6↔2.8, p< 0.05) while black rectal adenocarcinoma IRs significantly decreased (APC -1.4, CI -2.6↔0.1, p< 0.05) (figure 1b). Colon adenocarcinoma IRs in whites significantly increased (APC 1.2, CI 0.8↔1.6, p< 0.05) compared to blacks (APC 0.5, CI 0.3↔1.3, p >0.05), but absolute IRs were significantly less (figure 1b).
Discussion: By focusing on adenocarcinomas and SEER 18 expanded race data, we report the most comprehensive assessment of EOCRC IRs in 40-49-year-olds and show absolute black rectal adenocarcinoma IRs are now 39% less than whites and colorectal adenocarcinoma IRs are the same.
One explanation is a 2005 study recommending screening black patients at age 45 and 2008 guidelines consolidating this threshold. However, with a negative APC (-1.4) over 2000-2017, other factors could be contributing to the decrease in rectal adenocarcinoma IRs. Overall, our study provides support that screening at 45 may also impact rising EOCRC in whites.
Figure: Figure 1. SEER 18 Colorectal and Subsite Adenocarcinoma Incidence Rates in Age 40-49 Black Americans versus White Americans over 2000-2017. In panel (a), the black bar indicates that in 2014, 2015, 2016, and 2017 incidence rate ratios were not significant (p>0.05) between whites and blacks, indicating incidence rates were not significantly different. In panel (b), the black bar indicates that each year over 2009-2017 incidence rate ratio differences were significant (p < 0.05), indicating incidence rates were significantly different. *APC significantly changing with p < 0.05 and confidence intervals (CI) set to 95%.
Disclosures: Eric Montminy indicated no relevant financial relationships. Meijiao Zhou indicated no relevant financial relationships. Lauren Maniscalco indicated no relevant financial relationships. Harrison Penrose indicated no relevant financial relationships. Swati Patel indicated no relevant financial relationships. Xiao-Cheng Wu indicated no relevant financial relationships. Jordan Karlitz: Exact Sciences – Consultant. Gastro Girl – Stockholder/Ownership Interest (excluding diversified mutual funds). Myriad Genetics – Consultant, Speaker's Bureau.
Eric M. Montminy, MD1, Meijiao Zhou, PhD, MPH2, Lauren Maniscalco, MPH3, Harrison Penrose, PhD1, Swati Patel, MD4, Xiao-Cheng Wu, MD, MPH3, Jordan J. Karlitz, MD, FACG5. P1316 - Colorectal Cancer Incidence Rates in 40-49-Year-Old White Americans Now Matches Incidence Rates in Black Americans, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.
