Cancer incidence and mortality in China in 2013: an analysis based on urbanization level

To explore the cancer patterns in areas with different urbanization rates (URR) in China with data from 255 population-based cancer registries in 2013, collected by the National Central Cancer Registry (NCCR).

There were 347 cancer registries submitted cancer incidence and deaths occurred in 2013 to NCCR. All those data were checked and evaluated based on the NCCR criteria of data quality, and qualified data from 255 registries were used for this analysis. According to the proportion of non-agricultural population, we divided cities/counties into 3 levels: high level, with URR equal to 70% and higher; median level, with URR between 30% and 70%; and low level, with URR equal to 30% and less. Cancer incidences and mortalities were calculated, stratified by gender and age groups in different areas. The national population of Fifth Census in 2000 and Segi's population were applied for age-standardized rates.

Qualified 255 cancer registries covered 226,494,490 populations. The percentage of cases morphologically verified (MV%) and death certificate-only cases (DCO%) were 68.04% and 1.74%, respectively, and the mortality to incidence rate ratio (M/I) was 0.62. A total of 644,487 new cancer cases and 399,275 cancer deaths from the 255 cancer registries were submitted to NCCR in 2013. The incidence rate was 284.55/100,000 (314.06/100,000 in males, 254.19/100,000 in females), and the age-standardized incidence rates by Chinese standard population (ASIRC) and by world standard population (ASIRW) were 190.10/100,000 and 186.24/100,000 with the cumulative incidence rate (0-74 age years old) of 21.60%. The cancer mortality was 176.28/100,000 (219.03/100,000 in males, 132.30/100,000 in females), and the age-standardized mortality rates by Chinese standard population (ASMRC) and by world standard population (ASMRW) were 110.91/100,000 and 109.92/100,000, and the cumulative mortality rate (0-74 age years old) was 12.43%. Low urbanization areas were high in crude cancer incidence and mortality rates, middle urbanization areas came next to it followed by high urbanization areas. After adjusted by age, there was a U-shaped association between age-standardized incidence (ASIRC and ASIRW) and the urbanized ratio with the middle urbanization areas having the lowest ASIRC and ASIRW. Unlike with the age-standardized incidence, the sort order of age-standardized mortality (ASMRC and ASMRW) among three urbanization areas was reversed completely from the crude mortality. Lung cancer was the most common cancer in all areas of 255 cancer registries, followed by stomach cancer, liver cancer, colorectal cancer and esophageal cancer with new cases of 130,700, 76,200, 63,800, 60,900 and 50,200 respectively. Lung cancer was also the leading cause of cancer death in all areas of 255 cancer registries for both males and females with the number of deaths of 72,200 and 34,100, respectively. Other cancer types with high mortality in males were liver cancer, stomach cancer, esophageal cancer and colorectal cancer. In females, stomach cancer was the second cause of cancer death, followed by liver cancer, colorectal cancer and breast cancer.

Along with the development of socioeconomics associated with urbanization, as well as the aging population, the incidence and mortality keep increasing in China. Cancer burden and patterns are different in each urbanization level. Cancer control strategies should be implemented referring to local urbanization status.