National and subnational incidence, mortality and associated factors of colorectal cancer in China: A systematic analysis and modelling study

Abstract

Background: Due to their known variation by geography and economic development, we aimed to evaluate the incidence and mortality of colorectal cancer (CRC) in China over the past decades and identify factors associated with CRC among the Chinese population to provide targeted information on disease prevention.

Methods: We conducted a systemic review and meta-analysis of epidemiolocal studies on the incidence, mortality, and associated factors of CRC among the Chinese population, extracting and synthesising data from eligible studies retrieved from seven global and Chinese databases. We pooled age-standardised incidence rates (ASIRs) and mortality rates (ASMRs) for each province, subregion, and the whole of China, and applied a joinpoint regression model and annual per cent changes (APCs) to estimate the trends of CRC incidence and mortality. We conducted random-effects meta-analyses to assess the effect estimates of identified associated risk factors.

Results: We included 493 articles; 271 provided data on CRC incidence or mortality, and 222 on associated risk factors. Overall, the ASIR of CRC in China increased from 2.75 to 19.39 (per 100 000 person-years) between 1972 and 2019 with a slowed-down growth rate (APC₁ = 5.75, APC₂ = 0.42), while the ASMR of CRC decreased from 12.00 to 7.95 (per 100 000 person-years) between 1974 and 2020 with a slight downward trend (APC = -0.89). We analysed 62 risk factors with synthesized data; 16 belonging to the categories of anthropometrics factors, lifestyle factors, dietary factors, personal histories and mental health conditions were graded to be associated with CRC risk among the Chinese population in the meta-analysis limited to the high-quality studies.

Conclusions: We found substantial variation of CRC burden across regions and provinces of China and identified several associated risk factors for CRC, which could help to guide the formulation of targeted disease prevention and control strategies.

Registration: PROSPERO: CRD42022346558.

Figure 1

Study selection and flowchart. Reason 1*: Reviews or other non-original studies, Reason 2*: Meeting reports, Reason 3*: Studies that are not population-based or not based in China, Reason 4*: Full text not found, Reason 5*: No relevant indicators were mentioned (incidence /mortality rates or risk factors for Colorectal cancer), Reason 6*: Multiple publications of the same study, Reason 7*: Not standardised or not standardised according to uniform standards. CNKI – China National Knowledge Infrastructure, CBM – China Biology Medicine disc, CRC – colorectal cancer.

Figure 2

Trends analysis on ASIR and ASMR of CRC in entire China. Panel A. Yearly age-standardised incidence (1972-2019) of colorectal cancer in China based on the joinpoint regression model. Panel B. Yearly age-standardised mortality rate (1974-2020) of colorectal cancer in China based on the joinpoint regression model. The solid dot indicates a joinpoint (turning point demarking significance). The age composition of the Chinese population in 2000 was used as the standard population. . An asterisk (*) symbol indicates P < 0.05. ASIR – age-standardised incidence rate, ASMR – age-standardised mortality rate, CRC – colorectal cancer, APC – annual percentage change.

Figure 3

The ASIR and ASMR of CRC in China between 2011 and 2015. Panel A. Age-standardised incidence rate (ASIR) of colorectal cancer for each province in China, 2011-2015. Panel B. Age-standardised mortality rate (ASMR) of colorectal cancer for each province in China, 2011-2015. The age-standardised rate was divided into five segments. The colour gradient represents the magnitude of the age-standardised rate, the darker the colour, the larger the rate. Provinces with no data are filled in with blank spaces. ASIR – age-standardised incidence rate, ASMR – age-standardised mortality rate, CRC – colorectal cancer.

Figure 4

Results of overall meta-analysis confined meta-analysis of high-quality studies on the association between environmental factors and CRC. Panel A. Results of the overall meta-analysis on the association between environmental factors and CRC. Panel B. Results of the confined meta-analysis of high-quality studies on the association between environmental factors and CRC. All the factors are classified into various categories: sociodemographic, anthropometrics, lifestyle, dietary intake, mental health condition, and personal history factors. Three different colored legends represent different three different associations. Grey represents no significant association, blue represents a negative correlation, indicating to be a protective factor, and red indicates a positive correlation, indicating to be a risk factor. Evidence class criteria: Convincing (class I): statistical significance with P < 1 × 10⁻⁶; included more than 1000 cases; I²<50%; 95% prediction intervals excluding the null value; no evidence of small study effects (P > 0.10) and excess significance bias (P > 0.10). Highly suggestive (class II): statistical significance with P < 1 × 10⁻³; included more than 1000 cases; the largest component study reporting a significant result (P < 0.05). Suggestive (class III): statistical significance with P < 1 × 10⁻³; included more than 1000 cases. Weak (class IV): statistical significance with P < 0.05. Non-significant: P > 0.05. CRC – colorectal cancer, BMI – body mass index, UFA – unsaturated fatty acids, SFA – saturated fatty acids, DII – dietary inflammatory index, NS – non-significant, OR – odds ratio, CI – confidence interval.