Joinpoint Analysis and Age–Period–Cohort Effect on Mortality of Colorectal Cancer in Iran From 1990 to 2021

Background Colorectal cancer reported the fourth most common cancer in Iran. The aim of this study was to describe the time trends of colorectal cancer mortality from 1990 to 2021, focusing on the effects of age, period, and cohort. Method Our data included the number of colorectal cancer deaths and population recorded by the global burden of disease (GBD) and categorized by 5‐year age groups from 1990 to 2021. Joinpoint regression and the age–period–cohort (APC) model were used to reflect temporal trend and effects of age, period, and cohort on colorectal cancer mortality, respectively. Results The crude mortality rate of colorectal cancer was significantly increased in men, with an average annual percentage change (AAPC) of 1.558% (95% confidence interval [CI]: 1.398%, 1.778%), while the crude mortality rate increased (AAPC = 1.340%; 95% CI: 1.215%, 1.465%) and the age‐standardized mortality rate decreased in women (AAPC = −0.307%; 95% CI: −0.460%, −0.152%). APC analysis showed that the risk of death increased with age in both genders (Coef 15–19 = −2.823 vs. Coef > 95 = 1.731 in men and Coef 15–19 = −2.628 vs. Coef > 95 = 1.964 in women) and time (Coef 1992–1996 = −0.385 vs. Coef 2017–2021 = 0.438 in men and Coef 1992–1996 = −0.271 vs. Coef 2017–2021 = 0.380 in women) and was lower in later‐born cohort (Coef 2002–2006 = −1.590 in men and Coef 2002–2006 = −1.543 in women) than earlier‐born cohort (Coef < 1901 = 1.458 in men and Coef < 1901 = 1.208 in women). Conclusions Due to the increasing trend from colorectal cancer mortality and age and period effects, it seems necessary to modify early detection strategies and increase public awareness to reduce the burden of this cancer.