202 Colorectal Cancer Incidence and Demographic Trends in Patients Less Than 50 Years Old in a Large Integrated Healthcare System

Abstract

INTRODUCTION: Recent studies show increasing incidence of colorectal cancer (CRC) in adults less than 50 years, though there is limited data about this population. The primary aim of this study was to calculate trends in CRC incidence and average annual percentage change (AAPC) in patients less than 50 years old within a regional integrated health care system. The secondary aim was to determine demographic trends associated with CRC incidence in this younger population. METHODS: This is a retrospective cross-sectional study of Kaiser Permanente Southern California (KPSC) members, age 20–49 years from 1996–2016. Unadjusted incidence rates and AAPC were calculated by age (20–29, 30–39, 40–49) and year, and stratified by Surveillance, Epidemiology, and End Results Program (SEER) staging (early stage SEER 0–II; late stage SEER III, IV, VII). Incidence rate ratios (IRR) were calculated based on gender (male, female), age (40–49, 20–39), race/ethnicity (white, Asian, black, Hispanic), and stratified by staging, and location (proximal, distal). RESULTS: Among 3,125,389 patients, there were 2,883 (0.09%) age 20–49 years diagnosed with CRC from 1996–2016. Incidence increased up to 2.9% annually; in 20–39 year-olds, late stage colon cancer increased 1.9% annually (95% CI: 0.3, 3.5; P < 0.0001) and late stage rectal cancer increased 3.9% annually (95% CI: 0.6, 7.2; P < 0.0001). Compared to 20–39 year-olds, 40–49 year-olds had up to 5× risk for CRC at any stage and location (IRR 5.86; 95% CI: 4.94, 6.95; P < 0.0001). Men had increased risk for CRC compared to women, with 45% increased risk for proximal tumors (IRR 1.45; 95% CI: 1.24, 1.71; P < 0.0001). Whites and Asians had increased risk for distal tumors, up to 2× risk (IRR 2.0; 95% CI: 1.64, 2.45; P < 0.0001). Both also had higher risk for rectal cancer, up to 2.22× risk (IRR 2.22; 95% CI: 1.84, 2.68; P < 0.0001) compared to Hispanics and up to 56% increased risk (IRR 1.56; 95% CI: 1.24, 1.98; P = 0.0002) compared to blacks. Compared to whites and Asians, blacks had up to 43% increased risk for proximal tumors (IRR 0.57; 95% CI: 0.42, 0.78; P = 0.0003). Hispanics had the lowest risk for CRC at all stages and locations. CONCLUSION: The CRC incidence in 20–49 year-olds are increasing, particularly in cases of late stage CRC and among patients between 40–49 years of age. Distribution of tumor location varied by sex as well as race/ethnicity. Further studying of these demographic trends may help inform future screening and prevention strategies.