Abstract:

Objective To analyze the disease burden of colorectal cancer （CRC） among young and middle-aged people in China from 1990 to 2021， and to explore the influence of age， period and cohort on the incidence and mortality of CRC in young and middle-aged people of China. Methods Data on CRC in patients aged 40-59 years in China from 1990 to 2021 were extracted from the Global Burden of Disease Study 2021 （GBD 2021） database. Statistics such as incidence rate， mortality rate， disability-adjusted life years （DALY）， and their corresponding age-standardized rates were calculated to analyze the CRC incidence and mortality in different age and sex groups of young and middle-aged Chinese young people from 1990 to 2021. The Joinpoint regression model was used to analyze the CRC incidence， the mortality and the DALY rate， as well as to calculate the annual percentage change （APC） and the average annual percentage change （AAPC）. The effects of three independent factors， namely age， period and cohort， on the incidence and mortality of CRC in young and middle-aged people of China were analyzed and evaluated through the age-period-cohort model. Results From 1990 to 2021， there was a remarkable upward trend in the incidence， mortality， and DALY of CRC among Chinese young and middle-aged adults. In 2021， the number of incidence cases of CRC among young and middle-aged people in China reached 181 000， and the number of deaths reached 57 900， which were 236.80% and 75.48% higher than those in 1990 （53 800 and 33 000， respectively）. During the same period， DALY increased by 62.59%， with the 55-59 age group having the largest increase at 83.35%. From 1990 to 2021， the age-standardized incidence rate （ASIR） increased by 49.04%， rising from 25.51/100 000 to 38.02/100 000， and the age-standardized mortality rate （ASMR） declined by 28.75%， decreasing from 17.01/100 000 to 12.12/100 000， respectively. The increase in ASIR was the greatest among the 40-44 age group， reaching 57.31%， while the decline in ASMR was the most significant among the 50-54 age group， amounting to 30.18%. However， the DALY rate declined by 26.66%， from 673.52/100 000 to 493.94/100 000. The decline in DALY was the greatest among the 50-54 age group， reaching 28.26%. Joinpoint regression model analysis showed that， from 1990 to 2021， the incidence of CRC in Chinese young and middle-aged adults rose on average by 1.32% annually， and the increase was higher in men （1.87%） than that in women （0.36%）. The mortality rate showed a downward trend， with an average annual decline of 1.10%， with a higher decline in women than in men （-2.14% vs. -0.50%）. The DALY rate showed a downward trend， with an average annual decline of 1.00%， and more decline in women than in men （-2.06% vs. -0.41%）. All of these trends were statistically significant （all P<0.001）. The age-period-cohort model analysis showed that， the net drift of CRC incidence was 1.21% （1.02%-1.41%） per year among Chinese young and middle-aged adults between 1990 and 2021， while the net drift in mortality was -1.40% （-1.59%--1.21%） per year. The impact of age on CRC incidence and mortality intensified with advancing age. Incidence attributable to age rose from 12.66% （11.90%- 13.46%） in the 40-44 age group to 56.68% （54.37%-59.08%） in the 55-59 age group. Similarly， mortality attributable to age increased from 6.47% （6.12%-6.85%） in the 40-44 age group to 25.74% （24.58%-26.96%） in the 55-59 age group. In all age groups， the role of CRC incidence and mortality attributable to age was higher in men than in women. Period effects on the RR value of CRC incidence showed a declining trend followed by an upward trend， with the highest risk during 2015-2019 （RR=1.36， 95%CI： 1.28-1.43）， using 2000-2004 as the reference. For mortality， period effects exhibited a declining trend， with the highest risk during 1990-1994 （RR=1.23， 95%CI： 1.15-1.32）， using 2000-2004 as the reference. Cohort effects indicated that later birth cohorts had higher incidence risks， with the highest incidence observed in the 1973-1977 birth cohort （RR=1.30， 95%CI： 1.16-1.45）， using the 1953-1957 birth cohort as the reference. Conversely， later birth cohorts had lower mortality risks， with the lowest mortality in the 1973-1977 birth cohort （RR=0.78， 95%CI： 0.69-0.88）， using the 1953-1957 birth cohort as the reference. Conclusions From 1990 to 2021， the changes in the disease burden of CRC among young and middle-aged people in China are manifested as an increase in standardized incidence rate and a decrease in standardized mortality rate. Meanwhile， there are gender differences in the trend of temporal changes. Age， period and cohort all have a significant impact on the incidence and mortality trends of colorectal cancer in young and middle-aged people. Research on the etiology of CRC should be strengthened， and targeted prevention and control strategies should be formulated.

Key words: Colorectal neoplasms, Young and middle-aged adults, Incidence, Mortality, Disability-adjusted life year, Time trends, Age-period-cohort effects