Incidence of colorectal cancer in the republic of Ireland: Trends and challenges.

e15696 Background: The incidence of early onset colorectal cancer (EOCRC; ≤50 years) is increasing globally, while the incidence of average onset colorectal cancer (AOCRC; colorectal cancer ≥ 50years) is stabilising and beginning to decline with increased screening uptake. In Ireland screening begins at 59 years. We analysed trends in incidence of colorectal cancer (CRC) in the Republic of Ireland over a twenty-eight year period. Methods: Epidemiological data pertaining to the incidence of CRC (ICD-10 C18-C20), was obtained from the National Cancer Registry of Ireland (NCRI) from January 1994 until December 2021. Additional information on age of diagnosis and tumour sidedness for the entire period was obtained, while data relating to stage and gender was available for the study period 1999 - 2018. Incidence rates were stratified by sex, age group (20-34, 35-49, and greater than 50 years), and tumour sidedness (right versus left side). Results: Between 1994 to 2021, there were 61,180 cases of colorectal cancer among adults ≥20 years in the Republic of Ireland. During that time, the incidence of EOCRC increased by 34%, while the incidence of AOCRC decreased by 12.2%. The age specific rate (ASPR) annual percentage change (APC) amongst those with EOCRC was 0.97 (CI 0.30 - 1.76) in females and 0.57 (CI 0.08 - 1.30) in males. The age specific rate (ASPR) APC in those with AOCRC was -0.60 (CI -1.03 - -0.15) in females and -0.70 in males (CI -1.18 - -0.16). There were significantly higher rates of stage III and stage IV disease at diagnosis in the EOCRC group compared to the AOCRC group. For instance, in the 20-34 age group, 64% of individuals in the EOCRC group presented with stage III or IV disease, compared to 49% in the AOCRC group. A higher percentage of left-sided colorectal cancers compared to right-sided ones was observed across all age groups across the entire study period. The proportion of males diagnosed was higher than females in all groups except in the 20-34 age group, where there was a higher percentage of females than males. The 5-year net survival rate increased for both sexes across all age groups during the study period. Conclusions: In line with global trends, the incidence of EOCRC across both sexes is increasing in Ireland, and such patients are diagnosed at a later stage than their AOCRC counterparts. Public health initiatives must focus on screening age and public and healthcare practitioner awareness of this concerning trend. In addition, undertaking large-scale epidemiological and genomic studies will be essential to improve understanding of this disease and inform new treatment strategies for this patient group with unique needs.