Changing trends in age and stage of colorectal cancer presentation in Ireland - From the nineties to noughties and beyond.

Background: Recent studies report incidence of colorectal (CRC) in younger adults (<50 years old) is increasing, and these patients are more likely to present with advanced disease. We performed a population-based analysis of these trends in an Irish population.

Methods: A retrospective analysis was performed of all patients with histologically confirmed CRC in Ireland, using data from the National Cancer Registry of Ireland (NCRI) [1994-2012, inclusive]. Trends in age-adjusted CRC incidence and stage at presentation were tabulated. Total and average age-adjusted annual percentage change (APC) in CRC rates were calculated using regression analysis, with age adjusted to the European standard population for trend analysis.

Results: A total of 39,528 cases were included. Throughout the entire study period the most common age of presentation was 70-79 years (32.5%, n = 12 829) with Stage II (27.5%, n = 10 851) CRC. Overall, an increase in incidence of CRC of 2.1% was observed. A significantly increased incidence in patients aged 20-29 years (APC = 9.17%; total change = 4.2%; p = 0.003) was identified from 1994 to 2012. Overall, in patients <50 years, the incidence of stage I colorectal cancer at presentation significantly reduced from 23.5% to 11.6% (p = 0.01). This was associated with a significant parallel rise in stage IV disease (11%-23%, p = 0.02) in this age group.

Conclusion: Increasing incidence of CRC in younger patient groups is observed in an Irish population, with an increase in advanced staged disease at presentation seen. Further studies should focus on identifying causality for this trend and identify potential targets for prevention going forward.