Increasing Incidence of Young-Onset Colorectal Carcinoma A 3-Country Population Analysis

BACKGROUND: The overall incidence of colorectal carcinoma is declining in Western populations; however, single country series demonstrate an increase in young-onset (<50 years) colorectal carcinoma. OBJECTIVE: The purpose of this study was to determine whether the pattern of increasing incidence of young-onset colorectal carcinoma is consistent across 3 Western populations. DESIGN: This is a population incidence study. SETTINGS: National cancer registries of New Zealand, Sweden, and Scotland were used. PATIENTS: The incidence of colorectal carcinoma was calculated from population data for 3 countries over 2 to 4 decades. MAIN OUTCOME MEASURES: The incidence of colorectal carcinoma was measured. Incidence rate ratios were determined and data were stratified by subsite (colon versus rectum), sex, and age (<50, 50-79, and >= 80 y). RESULTS: Overall colorectal carcinoma rates declined in New Zealand, remained stable in Scotland, and increased in Sweden. In all 3 populations, there was an increasing incidence of rectal carcinoma in those aged <50 years. Young-onset rectal carcinoma increased in New Zealand (1995-2012: incidence rate ratio = 1.18 (men) and 1.13 (women)), with declining incidence in all other age groups. Colon carcinoma did not increase in the population aged <50 years, with the exception of distal colonic carcinoma in men. Overall, rectal carcinoma incidence increased (1970-2014) in Sweden; however, increases in those <50 years of age exceeded increases in other age groups (incidence rate ratio = 1.14 (males) and 1.12 (females)). Distal colon carcinoma increases were most marked in the population aged <50 years. In Scotland (1990-2014), young-onset rectal carcinoma incidence increased (incidence rate ratio = 1.23 (males) and 1.27 (females)), with a smaller increase in colon carcinoma. LIMITATIONS: Limitations include its registry-based, population incidence research. CONCLUSIONS: This study shows an increase in young-onset rectal carcinoma in 3 national populations; this observation may provide a focus for looking at the role of environmental influences on the etiology of this increase and therefore to explore strategies for prevention. See Video Abstract at http://links.lww.com/DCR/B194.