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Abstract

Background

China is facing the challenges of an expanding ageing population and the impact of rapid urbanization, cancer rates are subsequently increasing. This study focuses on the changes of the ageing population and projects the incidence of common ageing-related cancers in the urban regions in China up to 2030.

Sources of data

Cancer incidence data and population statistics in China were extracted from the International Agency for Research on Cancer.

Areas of agreement

Due to improving longevity in China, continuous and remarkable increasing trends for the lung, colorectal and prostate cancers are expected.

Growing points

The rate of expanding ageing population was taken into account when predicting the trend of cancer incidence; the estimations of ageing-related cancers were more factual and significant than using the conventional approach of age standardization.

Areas timely for developing research

The incidence rates of lung, colorectal and prostate cancers will continue to rise in the future decades due to the rise of ageing population. Lifestyle modification such as cutting tobacco smoking rates and promoting healthier diets as well as cancer screening programs should be a health system priority in order to decrease the growing burden of cancer-related mortality and morbidity.

ageing population, lung cancer, colorectal cancer, stomach cancer, prostate cancer

Introduction

China has been ranked as the most populous country in the world with a population of 1.36 billion, 18% of the world's population.1 Like other countries, China is seeing an expanding ageing population. Although the overall population growth rate decreased from 1.8% in 1960 to 0.5% in 2015, the growth for the population aged over 65 had increased from 4% in 1960 to 10% in 2015.1 The one-child family policy, introduced in 1979, has further contributed to the problem of the uneven ageing structure.2 Thus, with improving life expectancy, China is facing a huge healthcare burden with ageing-related diseases such as cancer or cardiovascular disease.

Urbanization has further aggravated the healthcare burden. The number of urban cities in China had increased at least 3-fold between 1978 and 2007.3 The Western diet, change of occupational pattern and air pollution are associated with the rise of cancer in China.4 The incidence rate of cancer increased from 215.8 per 100 000 in 2003 to 250.3 per 100 000 in 2011.5,6 According to the Chinese National Office for Cancer Prevention and Control and the National Central Cancer Registry estimation, there were ~4.3 million cancers diagnosed in China in 2015. Although population growth and change of population demographical structure are the driving forces to increase cancer incidences, many studies have made projections of cancer trends7–9 using only age-standardized rates without considering the rate of population growth.10

This paper focuses on the change of population structure among the ageing population (i.e. the proportional change of population with age 65+ along the years) and makes projections for the common ageing-related cancers in urban regions in China. Our expectation is that the growth of the ageing population will make differential impacts on the burdens of different cancers, and this information will be important for prioritizing the limited healthcare resources of the future health system.

Methods

Data extraction

The database from the International Agency for Research on Cancer (IARC) World Health Organization11 provided incidences of 27 cancers and population statistics from 102 cancer registries in 39 countries worldwide; the year of coverage was varied by registries. All cancer registries in China were included since the earliest common reported year; so data from each cancer registry could be combined.

Cancer selection

The cancers ranked as the top-10 were separately selected for both sexes then combined as the total cancer incidences. As this study focuses on the cancer projection for ageing populations, cancers were not included if: (i) ageing is not a major risk factor for the cancer or (ii) the cancer incidences were shifting to the younger generation. If the cancer incidence rate in those aged 65+ was less than double of those in other age groups, we assumed that ageing was not the major risk factor for the future cancer burden. If the incidence rates in those aged 65+ were decreasing over the years, whereas the rates in any other age group were increasing, we assumed that the cancer incidences were shifting to the younger generations.

Statistical analysis

Projection models were constructed to estimate the cancer trends up to 2030. Cancer incidences and sizes of population were independently projected by sex and age groups and then combined as the overall incidence. Auto-Regressive Integrated Moving Average (ARIMA) models were constructed to project cancer incidence and populations with the historical cancer incidence rates; cancer incidences and population sizes were the projection parameters. The Kwiatkowski–Phillips–Schmidt–Shin (KPSS) test and Akaike Information Criterion (AIC) value were used to determine the model validity and goodness-of-fit. When the P-value of KPSS >0.05 represented that data fulfilled the assumption of trend stationary12 and the model with minimum AIC value was selected as the best-fit model. Otherwise, linear regression using least squares method was applied, i.e. ARIMA model without auto-regressive and moving average functions. Age-standardized incidence rates and incidence rates for age 65+ were combined in each projected year and plotted against time. As the projection parameters were presented in 5-year intervals in IARC, local polynomial regression was used to smooth the projected line across the intervals.13 The trends of incidence rates of age 65+ were further weighted by the increased elderly population (i.e. a ratio of increased 65+ population with reference to the year of 1993), and this incidence rate was defined as an ‘ageing-adjusted incidence rate’ for comparison. The conceptual framework for ageing-adjusted incidence rate was also presented (Appendix 1). The same methodology was also applied in our previous work for global comparison on colorectal cancer trends.14 All incidence rates were calculated as cases per 100 000 persons and plotted up to 2030 using statistical software R (Version 3.2.1). Chi-square test was used to compare the increasing or decreasing trends of incidence rates, and statistical significance was obtained at P < 0.05.

Results

Demographic details

Cancer data from three urban regions in China were available from IARC, including Hong Kong, Shanghai and Jiashan. The registries reported data from 1988 to 2007 in Hong Kong and in Shanghai, and from 1993 to 2007 in Jiashan. Therefore, 15-year historical cancer incidence data from 1993 was used to develop projection models in this study. Hong Kong is a city on the southern part of China with a land mass of around 1104 km2. The reported population growth was 17%, increasing from 5.9 million in 1993 to 6.9 million in 2007 (Table 1). Shanghai is a city on the eastern part of China covering ~7037 km2. The reported population size decreased by 9% from 6.8 million in 1993 to 6.2 million in 2007. Jiashan is a region next to Shanghai with land size ~506 km2. The reported population were increased by 2% from 0.37 million in 1993 to 0.38 million in 2007. Male to female ratios were around 1:1 in all areas with a slightly increasing female population. The total population of those 65+ in the three regions was 13 044 738 (10.7% of the total population) in 1993, and increased to 13 449 669 (13.9% of the total population) in 2007 thus the proportions of age 65+ increased almost 30% in the 15-year period.

Table 1

Demographics of the three selected region

Land sizeHong KongShanghaiJiashanTotal
1104 km27037 km2506 km27952.1 km2
Year19932007199320071993200719932007
Population (dataset) 5 901 000 6 916 300 6 769 861 6 152 359 373 877 381 010 13 044 738 13 449 669 
Proportion of age 65 + (%) 9.25 12.61 12.08 15.34 8.43 12.89 10.70 13.87 
M:F 1:0.98 1:1.11 1:0.96 1: 0.99 1:0.98 1: 1.01 1:0.97 1:1.05 
Population (official) 5 998 000 6 916 300 13 810 000 13 588 600 373 900 380 700 20 181 900 20 885 600 
Average annual salary (USD) 13 324 17 427 678 4710 817 3072 309* 1823* 
GDP (USD) 12 billion 59 billion 18 billion 170 billion 203 000 2.5 billion 428 billion* 3573 billion* 
Land sizeHong KongShanghaiJiashanTotal
1104 km27037 km2506 km27952.1 km2
Year19932007199320071993200719932007
Population (dataset) 5 901 000 6 916 300 6 769 861 6 152 359 373 877 381 010 13 044 738 13 449 669 
Proportion of age 65 + (%) 9.25 12.61 12.08 15.34 8.43 12.89 10.70 13.87 
M:F 1:0.98 1:1.11 1:0.96 1: 0.99 1:0.98 1: 1.01 1:0.97 1:1.05 
Population (official) 5 998 000 6 916 300 13 810 000 13 588 600 373 900 380 700 20 181 900 20 885 600 
Average annual salary (USD) 13 324 17 427 678 4710 817 3072 309* 1823* 
GDP (USD) 12 billion 59 billion 18 billion 170 billion 203 000 2.5 billion 428 billion* 3573 billion* 

*Data of whole China.

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Table 1

Demographics of the three selected region

Land sizeHong KongShanghaiJiashanTotal
1104 km27037 km2506 km27952.1 km2
Year19932007199320071993200719932007
Population (dataset) 5 901 000 6 916 300 6 769 861 6 152 359 373 877 381 010 13 044 738 13 449 669 
Proportion of age 65 + (%) 9.25 12.61 12.08 15.34 8.43 12.89 10.70 13.87 
M:F 1:0.98 1:1.11 1:0.96 1: 0.99 1:0.98 1: 1.01 1:0.97 1:1.05 
Population (official) 5 998 000 6 916 300 13 810 000 13 588 600 373 900 380 700 20 181 900 20 885 600 
Average annual salary (USD) 13 324 17 427 678 4710 817 3072 309* 1823* 
GDP (USD) 12 billion 59 billion 18 billion 170 billion 203 000 2.5 billion 428 billion* 3573 billion* 
Land sizeHong KongShanghaiJiashanTotal
1104 km27037 km2506 km27952.1 km2
Year19932007199320071993200719932007
Population (dataset) 5 901 000 6 916 300 6 769 861 6 152 359 373 877 381 010 13 044 738 13 449 669 
Proportion of age 65 + (%) 9.25 12.61 12.08 15.34 8.43 12.89 10.70 13.87 
M:F 1:0.98 1:1.11 1:0.96 1: 0.99 1:0.98 1: 1.01 1:0.97 1:1.05 
Population (official) 5 998 000 6 916 300 13 810 000 13 588 600 373 900 380 700 20 181 900 20 885 600 
Average annual salary (USD) 13 324 17 427 678 4710 817 3072 309* 1823* 
GDP (USD) 12 billion 59 billion 18 billion 170 billion 203 000 2.5 billion 428 billion* 3573 billion* 

*Data of whole China.

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Selection for the cancers

A total of 15 cancers were selected from the top-10 ranked cancers by sex (Appendix 2). Incidence rates of each cancer were plotted against the years between 1993 and 2007 by age groups. Seven cancers were ageing related with no incidence shift to young generation (Table 2), including lung, stomach, liver, colorectal, esophagus, prostate and pancreatic cancer. Although there were certain numbers of patients with liver or breast cancer, these cancers were common in younger generations; and therefore, they were finally excluded in this study.

Table 2

Cancer selection for the model projection with adjustment on ageing population (incidence rates across the age groups shown in Appendix 4)

CancerIncidence rates dominated* in age 65+Incidences shifting† to young generationSelected‡ for projection modeling
Lung Yes No Yes 
Stomach Yes No Yes 
Esophagus Yes No Yes 
 Liver No No No 
Colorectal Yes No Yes 
 Breast No No No 
 Brain and CNS No No No 
 Cervix uteri No Yes No 
Pancreas Yes No Yes 
 Thyroid No No No 
 Lymphoma No No No 
Bladder Yes No Yes 
 Corpus uteri No No No 
Prostate Yes No Yes 
 Ovary No No No 
CancerIncidence rates dominated* in age 65+Incidences shifting† to young generationSelected‡ for projection modeling
Lung Yes No Yes 
Stomach Yes No Yes 
Esophagus Yes No Yes 
 Liver No No No 
Colorectal Yes No Yes 
 Breast No No No 
 Brain and CNS No No No 
 Cervix uteri No Yes No 
Pancreas Yes No Yes 
 Thyroid No No No 
 Lymphoma No No No 
Bladder Yes No Yes 
 Corpus uteri No No No 
Prostate Yes No Yes 
 Ovary No No No 

CNS, central nervous system.

*The incidence rate in age 65+ is more than double of those in other age groups.

†The incidence rate in age 65+ is decreasing over the years, whereas the rate in any other age group is increasing.

‡Cancer is selected if its incidence rate dominated in age 65+, and the incidences were not shifted to young generation.

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Table 2

Cancer selection for the model projection with adjustment on ageing population (incidence rates across the age groups shown in Appendix 4)

CancerIncidence rates dominated* in age 65+Incidences shifting† to young generationSelected‡ for projection modeling
Lung Yes No Yes 
Stomach Yes No Yes 
Esophagus Yes No Yes 
 Liver No No No 
Colorectal Yes No Yes 
 Breast No No No 
 Brain and CNS No No No 
 Cervix uteri No Yes No 
Pancreas Yes No Yes 
 Thyroid No No No 
 Lymphoma No No No 
Bladder Yes No Yes 
 Corpus uteri No No No 
Prostate Yes No Yes 
 Ovary No No No 
CancerIncidence rates dominated* in age 65+Incidences shifting† to young generationSelected‡ for projection modeling
Lung Yes No Yes 
Stomach Yes No Yes 
Esophagus Yes No Yes 
 Liver No No No 
Colorectal Yes No Yes 
 Breast No No No 
 Brain and CNS No No No 
 Cervix uteri No Yes No 
Pancreas Yes No Yes 
 Thyroid No No No 
 Lymphoma No No No 
Bladder Yes No Yes 
 Corpus uteri No No No 
Prostate Yes No Yes 
 Ovary No No No 

CNS, central nervous system.

*The incidence rate in age 65+ is more than double of those in other age groups.

†The incidence rate in age 65+ is decreasing over the years, whereas the rate in any other age group is increasing.

‡Cancer is selected if its incidence rate dominated in age 65+, and the incidences were not shifted to young generation.

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Trends of colorectal cancer with or without ageing effect in China

To distinguish the difference among the age-standardized incidence rates, the incidence rates of age 65+ and the ageing-adjusted incidence rates of age 65+, the figures on colorectal cancer are presented as a demonstration (Fig. 1). The age-standardized incidence rates gradually increased from 27.5/100 000 in 1993 to 33.8/100 000 in 2007 (black line). When we only focus on the population of age 65+, the colorectal cancer incidence rates were 176/100 000 in 1993 and 260/100 000 in 2007 (blue line). When the relative ratio of 65+ was fitted into the incidence rates, the ageing-adjusted incidence rate showed an increasing trend and was raised to 337/100 000 in 2007 (dotted-blue line). These incidence rates were further projected to 2030, and the ageing-adjusted incidence rate was then expected to be 502/100 000.
Fig. 1
Comparison among age-standardized incidence rates, incidence rate of age 65+ and ageing-adjusted incidence rate of age 65+ with increasing elderly population in all regions.
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Comparison among age-standardized incidence rates, incidence rate of age 65+ and ageing-adjusted incidence rate of age 65+ with increasing elderly population in all regions.

Fig. 1
Comparison among age-standardized incidence rates, incidence rate of age 65+ and ageing-adjusted incidence rate of age 65+ with increasing elderly population in all regions.
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Comparison among age-standardized incidence rates, incidence rate of age 65+ and ageing-adjusted incidence rate of age 65+ with increasing elderly population in all regions.

Trends of other cancers in China

For lung cancer, the age-standardized incidence rates showed a gradual decrease from 45.6/100 000 in 1993 to 33.8/100 000 in 2030, but the ageing-adjusted incidence rates for age 65+ showed an increasing trend from 344/100 000 in 1993 to 511/100 000 in 2030 (Fig. 2). For stomach cancer, although the age-standardized incidence rates showed a decreasing trend, the ageing-adjusted incidence rates showed a stable trend. There were much lower incidence rates in esophagus, bladder, prostate and pancreas cancers in 1993 (Table 3), but only prostate cancer showed both increasing age-standardized incidence rate and ageing-adjusted incidence rate of age 65+ (Fig. 2). The ageing-adjusted incidence rate for prostate cancer was expected to be even higher than that for stomach cancer in 2030.
Fig. 2
Projected cancer incidence over the period until 2030 in China.
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Projected cancer incidence over the period until 2030 in China.

Fig. 2
Projected cancer incidence over the period until 2030 in China.
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Projected cancer incidence over the period until 2030 in China.

Table 3

Projected cancer incidence rates to 2030 in the selected urban regions in China

CancerYearAge-standardized incidence rate/100 000Incidence rate of age 65+/100 000 (a)Population of 65+/overall population (%)Relatively increased in the ratio of age 65+ (b)Ageing-adjusted incidence rate of age 65+/100 000 (c) = (a) × (b)
Colorectal 1993 27.5 175.5 10.70 1.00 175.5 
 2007 33.8 259.9 13.87 1.30 336.8 
 2015 35.2 285.8 15.04 1.41 401.6 
 2030 37.5 320.5 16.76 1.57 502.3 
Lung 1993 45.6 343.8 10.70 1.00 343.8 
 2007 36.3 299.2 13.87 1.30 387.7 
 2015 36.0 318.8 15.04 1.41 448.1 
 2030 33.8 326.4 16.76 1.57 511.4 
Stomach 1993 24.5 165.5 10.70 1.00 165.5 
 2007 16.2 122.1 13.87 1.30 158.3 
 2015 14.9 119.3 15.04 1.41 167.7 
 2030 12.3 107.6 16.76 1.57 168.6 
Esophagus 1993 8.6 64.1 10.70 1.00 64.1 
 2007 4.5 34.9 13.87 1.30 45.2 
 2015 4.0 35.5 15.04 1.41 49.9 
 2030 3.1 30.3 16.76 1.57 47.5 
Bladder 1993 6.2 49.6 10.70 1.00 49.6 
 2007 4.9 46.1 13.87 1.30 59.8 
 2015 5.2 53.0 15.04 1.41 74.4 
 2030 4.9 54.5 16.76 1.57 85.5 
Prostate 1993 2.7 26.2 10.70 1.00 26.2 
 2007 8.6 91.7 13.87 1.30 118.9 
 2015 9.4 102.7 15.04 1.41 144.3 
 2030 11.6 122.9 16.76 1.57 192.6 
Pancreas 1993 5.0 38.3 10.70 1.00 38.3 
 2007 6.0 48.8 13.87 1.30 63.2 
 2015 6.0 55.3 15.04 1.41 77.7 
 2030 6.3 61.3 16.76 1.57 96.1 
CancerYearAge-standardized incidence rate/100 000Incidence rate of age 65+/100 000 (a)Population of 65+/overall population (%)Relatively increased in the ratio of age 65+ (b)Ageing-adjusted incidence rate of age 65+/100 000 (c) = (a) × (b)
Colorectal 1993 27.5 175.5 10.70 1.00 175.5 
 2007 33.8 259.9 13.87 1.30 336.8 
 2015 35.2 285.8 15.04 1.41 401.6 
 2030 37.5 320.5 16.76 1.57 502.3 
Lung 1993 45.6 343.8 10.70 1.00 343.8 
 2007 36.3 299.2 13.87 1.30 387.7 
 2015 36.0 318.8 15.04 1.41 448.1 
 2030 33.8 326.4 16.76 1.57 511.4 
Stomach 1993 24.5 165.5 10.70 1.00 165.5 
 2007 16.2 122.1 13.87 1.30 158.3 
 2015 14.9 119.3 15.04 1.41 167.7 
 2030 12.3 107.6 16.76 1.57 168.6 
Esophagus 1993 8.6 64.1 10.70 1.00 64.1 
 2007 4.5 34.9 13.87 1.30 45.2 
 2015 4.0 35.5 15.04 1.41 49.9 
 2030 3.1 30.3 16.76 1.57 47.5 
Bladder 1993 6.2 49.6 10.70 1.00 49.6 
 2007 4.9 46.1 13.87 1.30 59.8 
 2015 5.2 53.0 15.04 1.41 74.4 
 2030 4.9 54.5 16.76 1.57 85.5 
Prostate 1993 2.7 26.2 10.70 1.00 26.2 
 2007 8.6 91.7 13.87 1.30 118.9 
 2015 9.4 102.7 15.04 1.41 144.3 
 2030 11.6 122.9 16.76 1.57 192.6 
Pancreas 1993 5.0 38.3 10.70 1.00 38.3 
 2007 6.0 48.8 13.87 1.30 63.2 
 2015 6.0 55.3 15.04 1.41 77.7 
 2030 6.3 61.3 16.76 1.57 96.1 
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Table 3

Projected cancer incidence rates to 2030 in the selected urban regions in China

CancerYearAge-standardized incidence rate/100 000Incidence rate of age 65+/100 000 (a)Population of 65+/overall population (%)Relatively increased in the ratio of age 65+ (b)Ageing-adjusted incidence rate of age 65+/100 000 (c) = (a) × (b)
Colorectal 1993 27.5 175.5 10.70 1.00 175.5 
 2007 33.8 259.9 13.87 1.30 336.8 
 2015 35.2 285.8 15.04 1.41 401.6 
 2030 37.5 320.5 16.76 1.57 502.3 
Lung 1993 45.6 343.8 10.70 1.00 343.8 
 2007 36.3 299.2 13.87 1.30 387.7 
 2015 36.0 318.8 15.04 1.41 448.1 
 2030 33.8 326.4 16.76 1.57 511.4 
Stomach 1993 24.5 165.5 10.70 1.00 165.5 
 2007 16.2 122.1 13.87 1.30 158.3 
 2015 14.9 119.3 15.04 1.41 167.7 
 2030 12.3 107.6 16.76 1.57 168.6 
Esophagus 1993 8.6 64.1 10.70 1.00 64.1 
 2007 4.5 34.9 13.87 1.30 45.2 
 2015 4.0 35.5 15.04 1.41 49.9 
 2030 3.1 30.3 16.76 1.57 47.5 
Bladder 1993 6.2 49.6 10.70 1.00 49.6 
 2007 4.9 46.1 13.87 1.30 59.8 
 2015 5.2 53.0 15.04 1.41 74.4 
 2030 4.9 54.5 16.76 1.57 85.5 
Prostate 1993 2.7 26.2 10.70 1.00 26.2 
 2007 8.6 91.7 13.87 1.30 118.9 
 2015 9.4 102.7 15.04 1.41 144.3 
 2030 11.6 122.9 16.76 1.57 192.6 
Pancreas 1993 5.0 38.3 10.70 1.00 38.3 
 2007 6.0 48.8 13.87 1.30 63.2 
 2015 6.0 55.3 15.04 1.41 77.7 
 2030 6.3 61.3 16.76 1.57 96.1 
CancerYearAge-standardized incidence rate/100 000Incidence rate of age 65+/100 000 (a)Population of 65+/overall population (%)Relatively increased in the ratio of age 65+ (b)Ageing-adjusted incidence rate of age 65+/100 000 (c) = (a) × (b)
Colorectal 1993 27.5 175.5 10.70 1.00 175.5 
 2007 33.8 259.9 13.87 1.30 336.8 
 2015 35.2 285.8 15.04 1.41 401.6 
 2030 37.5 320.5 16.76 1.57 502.3 
Lung 1993 45.6 343.8 10.70 1.00 343.8 
 2007 36.3 299.2 13.87 1.30 387.7 
 2015 36.0 318.8 15.04 1.41 448.1 
 2030 33.8 326.4 16.76 1.57 511.4 
Stomach 1993 24.5 165.5 10.70 1.00 165.5 
 2007 16.2 122.1 13.87 1.30 158.3 
 2015 14.9 119.3 15.04 1.41 167.7 
 2030 12.3 107.6 16.76 1.57 168.6 
Esophagus 1993 8.6 64.1 10.70 1.00 64.1 
 2007 4.5 34.9 13.87 1.30 45.2 
 2015 4.0 35.5 15.04 1.41 49.9 
 2030 3.1 30.3 16.76 1.57 47.5 
Bladder 1993 6.2 49.6 10.70 1.00 49.6 
 2007 4.9 46.1 13.87 1.30 59.8 
 2015 5.2 53.0 15.04 1.41 74.4 
 2030 4.9 54.5 16.76 1.57 85.5 
Prostate 1993 2.7 26.2 10.70 1.00 26.2 
 2007 8.6 91.7 13.87 1.30 118.9 
 2015 9.4 102.7 15.04 1.41 144.3 
 2030 11.6 122.9 16.76 1.57 192.6 
Pancreas 1993 5.0 38.3 10.70 1.00 38.3 
 2007 6.0 48.8 13.87 1.30 63.2 
 2015 6.0 55.3 15.04 1.41 77.7 
 2030 6.3 61.3 16.76 1.57 96.1 
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Subgroup analyses by sex

For male, colorectal, lung, prostate and pancreas cancers showed increasing trends of ageing-adjusted incidence rates. Colorectal cancer had the greatest increment of the ageing-adjusted incidence rate of from 197.1/100 000 in 1993 to 658.5/100 000 in 2030 (Appendix 3). For female, colorectal and pancreas cancers showed increasing trends of ageing-adjusted incidence rates. The ageing-adjusted incidence rate of colorectal cancer increased from 157.9/100 000 in 1993 to 386.3/100 000 in 2030. Colorectal cancer would be much affected by the ageing of both Chinese male and female population.

Comparison across cancer ranking

Among the cancers included in this study, lung cancer started with the highest incidence rates in 1993. However, with the projected incidence related to change in ageing structure, colorectal cancer will have comparable ageing-adjusted incidence rates (i.e. 511/100 000 for lung and 502/100 000 for colorectal cancer). The incidences of prostate cancer will continuously increase and overtake the rank of stomach cancer by 2030, whereas cancers of esophagus, bladder and pancreas would remain at the low incidence rates, even if growth of the ageing population was considered.

Discussion

This study compared the trends on colorectal, lung, stomach, esophagus, pancreas, bladder and prostate cancers with adjustment for the ageing population in China. The incidence of colorectal cancer and lung cancer is projected to increase over time due to advanced ageing and population growth. Although the current incidence rates of prostate cancer are not alarming, this study shows that the trend of prostate cancer will rise with the ageing of the population, and will become more common than stomach cancer by 2030. Other cancers will remain at the low incidence rates even though the ageing population is expanding.

Epidemiologic studies indicate that environment and lifestyle are the major determinants of the geographical distribution of cancer.15–17 Some regions in China have developed at a faster pace than others as a result of urbanization and economic growth which have introduced the rural–urban health differential.18 Although studies have reported that esophagus and stomach were the major sites for cancer in China's rural areas,7,19,20 increasing trends for these cancers were not observed in this study because we focused on three urban areas and cancer registry data from rural areas were not included. While it would be interesting to consider the cancer trends in rural areas, the data from the WHO are limited. Breast cancer is a common cancer among Chinese women; the ageing effect on breast cancer was not significant (Appendix 4). As the current projection model focuses on the rate of expanding population age 65 or above, the ageing-related projection model would not be applicable in this case. Brey et al. have forecasted the global cancer mortality and reported that the number one cancer-caused of death in China in 2030 will be lung cancer for both male and female.21 Our study showed similar results that lung cancer will be the most common cancer in China by that time. The high level of lung cancer may be associated with tobacco smoking and environmental pollution. In 2010, there were an estimated 301 million smokers in China, 52.9% and 2.4% of the male and female populations, respectively, making this country the largest consumer of tobacco in the world.22 The IARC has discussed the causal effect of air pollution to lung cancer and stated that exposure to ambient fine particles (PM 2.5) was estimated to have contributed 223 000 deaths from lung cancer. More than half of the lung cancer deaths attributable to ambient PM 2.5 were estimated to have been in China and other East Asian countries.23,24 Although Chinese women had a relatively low prevalence of tobacco smoking rate, a meta-analysis has reported that cooking smoke was a major risk factor for lung cancer in Chinese women.25 If smoking and solid-fuel use remain at current levels, Lin HH projected that there will be 18 million lung cancer deaths in China in 2033.26

Colorectal cancer is the second most common cancer; however, the ageing-adjusted incidence rates of lung and colorectal cancer are very similar but there is a steep incline in colorectal cancer. The epidemic of colorectal cancer may be strongly influenced by tobacco use and the Western dietary pattern resulting from urbanization.4,27 Colorectal cancer is a preventable cancer; the incidence can be reduced by screening and removal of precancerous polyp, which can also improve the survival rate of colorectal cancer by the early detection and treatment at early-stage.28 However, population-based colorectal cancer screening program is not available in China. For the generation whose rates continue to rise, early detection as well as health system provision need to be considered by policy makers. For future generations, facing greater longevity, efforts to prevent cancer from occurring need to continue to be prioritized.

The strength of this study is the projection on the cancer trends with adjustment on the future change of ageing proportions. However, there are several limitations. First, only secondary data from IARC were analyzed; the data quality and completeness cannot be guaranteed. For example, the cancer data from Shanghai only included 9 out of 16 towns representing half of the total population of the city. Second, the cancer incidences were reported until 2007 at the time of analysis. The accuracy of projected results may be affected by the length of historical data; it will be worth updating the result when the WHO releases more updated figures. Third, although the incidence rates are adjusted for age and sex, the future cancer incidences will still be affected by many other factors, such as smoking cessation rates, development and acceptance of cancer screening programs, and changes of lifestyle. Fourth, the three included urban regions are economically developed ones and probably approaching the highest degree of aging in China. As China is developing rapidly, we assume that the overall development level of China in 2030 will be comparable with the three included regions in order to make this study result extrapolate the general population in all urban regions of China.

In conclusion, our data suggest that due to the changes of ageing population the incidence rates of colorectal, lung and prostate cancers will continue to rise in future decades, whereas stomach, esophagus, pancreas and bladder cancers will remain at current lower incidence rates in the urban regions in China. This increased burden of disease among those over 65 needs to be addressed through primary prevention at younger age groups and through appropriate service provision for detection and treatment for older groups in the population.

Conflict of interest statement

Prof S. Griffiths is a commissioning editor for BMB.There is no other conflict of interest to be declared.

Funding

This is a self-initiated study. No funding was received.

Appendixes

Appendix 1
Conceptual framework.
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Conceptual framework.

Appendix 1
Conceptual framework.
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Conceptual framework.

Appendix 2
The top-10 cancer in China in 2015 (in thousands).
Open in new tabDownload slide

The top-10 cancer in China in 2015 (in thousands).

Appendix 2
The top-10 cancer in China in 2015 (in thousands).
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The top-10 cancer in China in 2015 (in thousands).

Appendix 4
Cancer incidences across the age groups.
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Cancer incidences across the age groups.

Appendix 4
Cancer incidences across the age groups.
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Cancer incidences across the age groups.

Appendix 3

Subgroup analyses by sex for the projected cancer incidence rates to 2030.

CancerYearAgeing-adjusted incidence rate of age 65+/100 000
MaleFemaleOverall
Colorectal 1993 197.1 157.9 175.5 
 2007 423.5 268.8 336.8 
 2015 515.3 315.1 401.6 
 2030 658.5 386.3 502.3 
Lung 1993 515.6 203.8 343.8 
 2007 591.0 231.5 387.7 
 2015 709.9 255.0 448.1 
 2030 830.9 282.5 511.4 
Stomach 1993 236.5 107.7 165.5 
 2007 225.1 106.6 158.3 
 2015 247.5 108.5 167.7 
 2030 247.8 111.1 168.6 
Esophagus 1993 99.3 35.4 64.1 
 2007 68.8 27.0 45.2 
 2015 81.0 27.0 49.9 
 2030 77.0 26.4 47.5 
Bladder 1993 79.0 25.6 49.6 
 2007 103.7 26.2 59.8 
 2015 132.8 31.7 74.4 
 2030 156.2 35.2 85.5 
Prostate 1993 58.2 NA 26.2 
 2007 275.5 NA 118.9 
 2015 343.6 NA 144.3 
 2030 467.1 NA 192.6 
Pancreas 1993 44.0 33.6 38.3 
 2007 76.3 52.9 63.2 
 2015 93.0 65.7 77.7 
 2030 117.5 79.7 96.1 
CancerYearAgeing-adjusted incidence rate of age 65+/100 000
MaleFemaleOverall
Colorectal 1993 197.1 157.9 175.5 
 2007 423.5 268.8 336.8 
 2015 515.3 315.1 401.6 
 2030 658.5 386.3 502.3 
Lung 1993 515.6 203.8 343.8 
 2007 591.0 231.5 387.7 
 2015 709.9 255.0 448.1 
 2030 830.9 282.5 511.4 
Stomach 1993 236.5 107.7 165.5 
 2007 225.1 106.6 158.3 
 2015 247.5 108.5 167.7 
 2030 247.8 111.1 168.6 
Esophagus 1993 99.3 35.4 64.1 
 2007 68.8 27.0 45.2 
 2015 81.0 27.0 49.9 
 2030 77.0 26.4 47.5 
Bladder 1993 79.0 25.6 49.6 
 2007 103.7 26.2 59.8 
 2015 132.8 31.7 74.4 
 2030 156.2 35.2 85.5 
Prostate 1993 58.2 NA 26.2 
 2007 275.5 NA 118.9 
 2015 343.6 NA 144.3 
 2030 467.1 NA 192.6 
Pancreas 1993 44.0 33.6 38.3 
 2007 76.3 52.9 63.2 
 2015 93.0 65.7 77.7 
 2030 117.5 79.7 96.1 

NA, not applicable.

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Appendix 3

Subgroup analyses by sex for the projected cancer incidence rates to 2030.

CancerYearAgeing-adjusted incidence rate of age 65+/100 000
MaleFemaleOverall
Colorectal 1993 197.1 157.9 175.5 
 2007 423.5 268.8 336.8 
 2015 515.3 315.1 401.6 
 2030 658.5 386.3 502.3 
Lung 1993 515.6 203.8 343.8 
 2007 591.0 231.5 387.7 
 2015 709.9 255.0 448.1 
 2030 830.9 282.5 511.4 
Stomach 1993 236.5 107.7 165.5 
 2007 225.1 106.6 158.3 
 2015 247.5 108.5 167.7 
 2030 247.8 111.1 168.6 
Esophagus 1993 99.3 35.4 64.1 
 2007 68.8 27.0 45.2 
 2015 81.0 27.0 49.9 
 2030 77.0 26.4 47.5 
Bladder 1993 79.0 25.6 49.6 
 2007 103.7 26.2 59.8 
 2015 132.8 31.7 74.4 
 2030 156.2 35.2 85.5 
Prostate 1993 58.2 NA 26.2 
 2007 275.5 NA 118.9 
 2015 343.6 NA 144.3 
 2030 467.1 NA 192.6 
Pancreas 1993 44.0 33.6 38.3 
 2007 76.3 52.9 63.2 
 2015 93.0 65.7 77.7 
 2030 117.5 79.7 96.1 
CancerYearAgeing-adjusted incidence rate of age 65+/100 000
MaleFemaleOverall
Colorectal 1993 197.1 157.9 175.5 
 2007 423.5 268.8 336.8 
 2015 515.3 315.1 401.6 
 2030 658.5 386.3 502.3 
Lung 1993 515.6 203.8 343.8 
 2007 591.0 231.5 387.7 
 2015 709.9 255.0 448.1 
 2030 830.9 282.5 511.4 
Stomach 1993 236.5 107.7 165.5 
 2007 225.1 106.6 158.3 
 2015 247.5 108.5 167.7 
 2030 247.8 111.1 168.6 
Esophagus 1993 99.3 35.4 64.1 
 2007 68.8 27.0 45.2 
 2015 81.0 27.0 49.9 
 2030 77.0 26.4 47.5 
Bladder 1993 79.0 25.6 49.6 
 2007 103.7 26.2 59.8 
 2015 132.8 31.7 74.4 
 2030 156.2 35.2 85.5 
Prostate 1993 58.2 NA 26.2 
 2007 275.5 NA 118.9 
 2015 343.6 NA 144.3 
 2030 467.1 NA 192.6 
Pancreas 1993 44.0 33.6 38.3 
 2007 76.3 52.9 63.2 
 2015 93.0 65.7 77.7 
 2030 117.5 79.7 96.1 

NA, not applicable.

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Appendix 2

The top-10 cancer in China in 2015 (in thousands).

CancerTotalMaleFemale
PositionICD-10Incidence (‘000)RankIncidence (‘000)RankIncidence (‘000)Rank
Lung C33–C34 733.3 1st 509.3 1st 224 2nd 
Stomach C16 679.1 2nd 477.7 2nd 201.4 3rd 
Esophagus C15 477.9 3rd 320.8 4th 157.2 5th 
Liver C22 466.1 4th 343.7 3rd 122.3 6th 
Colorectal C18–C21 376.3 5th 215.7 5th 160.6 4th 
Breast C50 272.4 6th 3.8 22nd 268.6 1st 
Brain and CNS C70–C72 101.6 7th 52.3 9th 49.3 11th 
Cervix C53 98.9 8th – – 98.9 7th 
Pancreas C25 90.1 9th 52.2 10th 37.9 12th 
Thyroid C73 90.0 10th 22.2 17th 67.9 8th 
Lymphoma C81–C85, C88, C90, C96 88.2 11th 53.0 8th 35.2 13th 
Bladder C67 80.5 12th 62.1 6th 18.4 17th 
Corpus uteri C54–C55 63.4 15th – – 63.4 9th 
Prostate C61 60.3 17th 60.3 7th – – 
Ovary C56 52.1 19th – – 52.1 10th 
CancerTotalMaleFemale
PositionICD-10Incidence (‘000)RankIncidence (‘000)RankIncidence (‘000)Rank
Lung C33–C34 733.3 1st 509.3 1st 224 2nd 
Stomach C16 679.1 2nd 477.7 2nd 201.4 3rd 
Esophagus C15 477.9 3rd 320.8 4th 157.2 5th 
Liver C22 466.1 4th 343.7 3rd 122.3 6th 
Colorectal C18–C21 376.3 5th 215.7 5th 160.6 4th 
Breast C50 272.4 6th 3.8 22nd 268.6 1st 
Brain and CNS C70–C72 101.6 7th 52.3 9th 49.3 11th 
Cervix C53 98.9 8th – – 98.9 7th 
Pancreas C25 90.1 9th 52.2 10th 37.9 12th 
Thyroid C73 90.0 10th 22.2 17th 67.9 8th 
Lymphoma C81–C85, C88, C90, C96 88.2 11th 53.0 8th 35.2 13th 
Bladder C67 80.5 12th 62.1 6th 18.4 17th 
Corpus uteri C54–C55 63.4 15th – – 63.4 9th 
Prostate C61 60.3 17th 60.3 7th – – 
Ovary C56 52.1 19th – – 52.1 10th 

Ref. Chen et al.7

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Appendix 2

The top-10 cancer in China in 2015 (in thousands).

CancerTotalMaleFemale
PositionICD-10Incidence (‘000)RankIncidence (‘000)RankIncidence (‘000)Rank
Lung C33–C34 733.3 1st 509.3 1st 224 2nd 
Stomach C16 679.1 2nd 477.7 2nd 201.4 3rd 
Esophagus C15 477.9 3rd 320.8 4th 157.2 5th 
Liver C22 466.1 4th 343.7 3rd 122.3 6th 
Colorectal C18–C21 376.3 5th 215.7 5th 160.6 4th 
Breast C50 272.4 6th 3.8 22nd 268.6 1st 
Brain and CNS C70–C72 101.6 7th 52.3 9th 49.3 11th 
Cervix C53 98.9 8th – – 98.9 7th 
Pancreas C25 90.1 9th 52.2 10th 37.9 12th 
Thyroid C73 90.0 10th 22.2 17th 67.9 8th 
Lymphoma C81–C85, C88, C90, C96 88.2 11th 53.0 8th 35.2 13th 
Bladder C67 80.5 12th 62.1 6th 18.4 17th 
Corpus uteri C54–C55 63.4 15th – – 63.4 9th 
Prostate C61 60.3 17th 60.3 7th – – 
Ovary C56 52.1 19th – – 52.1 10th 
CancerTotalMaleFemale
PositionICD-10Incidence (‘000)RankIncidence (‘000)RankIncidence (‘000)Rank
Lung C33–C34 733.3 1st 509.3 1st 224 2nd 
Stomach C16 679.1 2nd 477.7 2nd 201.4 3rd 
Esophagus C15 477.9 3rd 320.8 4th 157.2 5th 
Liver C22 466.1 4th 343.7 3rd 122.3 6th 
Colorectal C18–C21 376.3 5th 215.7 5th 160.6 4th 
Breast C50 272.4 6th 3.8 22nd 268.6 1st 
Brain and CNS C70–C72 101.6 7th 52.3 9th 49.3 11th 
Cervix C53 98.9 8th – – 98.9 7th 
Pancreas C25 90.1 9th 52.2 10th 37.9 12th 
Thyroid C73 90.0 10th 22.2 17th 67.9 8th 
Lymphoma C81–C85, C88, C90, C96 88.2 11th 53.0 8th 35.2 13th 
Bladder C67 80.5 12th 62.1 6th 18.4 17th 
Corpus uteri C54–C55 63.4 15th – – 63.4 9th 
Prostate C61 60.3 17th 60.3 7th – – 
Ovary C56 52.1 19th – – 52.1 10th 

Ref. Chen et al.7

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