Investigating temporal patterns of colorectal cancer incidence in Spain: a comprehensive analysis of age, period and cohort effects, 1990-2019

Aim: this study aimed to evaluate how age, period, and cohort (A-P-C) impact on colorectal cancer (CRC) incidence in Spain from 1990 to 2019. Method: using data from the Global Burden of Disease Study 2019, joinpoint analysis was used to identify longterm trends and A-P-C modelling to quantify net drift, local drift, longitudinal age curves, and rate ratios (RRs) of period and cohort effects. Results: CRC incidence increased steadily in Spain from 1990 to 2019, with a more significant rise in males than in females. The age standardized rates rose from 84.9 to 129.3 cases per 100,000 in males and from 56.9 to 70.3 cases per 100,000 in females. Joinpoint analysis revealed distinct patterns for men and women: male incidence showed three phases (a surge until 1995, a slowdown until 2012, and a subsequent decrease) while female incidence showed a single increase until 2011 and then stabilized. Local drifts increased in all age groups over 45, with stability in males under 45 and a decrease in females aged 30-39. The risk of CRC increased with age, with males consistently having a higher risk than females. The risk of CRC increased over time for both men and women but at different rates. The risk for cohorts born in the early to mid-20th century peaked in the 1960s and remained stable until the late 1990s. Conclusion: the increasing incidence of CRC in Spain, with distinct patterns by gender and birth cohort, underlines the importance of preventive strategies adapted to temporal and demographic variations to address this public health challenge.