Long-term trends of oral cancer incidence in China from 2004 to 2018 by region and sex: age-period-cohort analysis and decomposition Analysis

<b>Abstract</b><b>Objective</b> This study aimed to analyze trends in oral cancer (OC) incidence in China from 2004 to 2018, identifying the contributing factors influencing these trends. Additionally, the epidemiological characteristics by region and sex were examined, and the effects of age, period, and cohort were explored.<b>Methods </b>OC data were sourced from the Chinese Cancer Registry Annual Reports for 2004 to 2018. Average Annual Percent Change (AAPC) and 95% confidence intervals (CI) were calculated using Joinpoint Regression Software to evaluate trends. OC incidence rate in registry areas, combined with national population data, were used to estimate new cases. The effect of age, period, and cohort on OC incidence was estimated by age-period-cohort model. A decomposition analysis identified factors influencing trends.<b>Results </b>From 2004 to 2018, the age-standardized incidence rate (ASIR) of OC showed an increasing trend in urban males, rural males, and rural females, while remaining stable in urban females, with males having higher ASIR than females. Additionally, the ASIR growth rate of OC in rural areas exceeded that in urban areas. The age-specific incidence rate curves show that the OC incidence rates in urban males and females generally increase with age, while in rural males and females, they peak at 82.5 years and then begin to decline. Using the 2009-2013 period as a reference, the period effect rate ratios (RR) for OC incidence in urban males, rural males, and females during 2004-2008 were greater than 1. Population growth contributed to the increase in OC in urban areas, whereas it was a major factor associated with the decrease in OC cases in rural areas.<b>Conclusion </b>From 2004 to 2018, the ASIR of OC in China showed an upward trend, with population growth being a key driver of the OC burden in urban areas. The burden of OC continues to increase, posing a serious threat to public health. Public health authorities need to implement more proactive prevention policies.