Descriptive Analysis of Death rate Trends
Figure 1 shows the age-standardized death rate of three cancers in China (A), Japan (B), the United States(C), and India (D) from 1990 to 2017. In China, all three cancers death rate show a slight upward trend and then decline. The ASDR of stomach cancer in China is particularly significantly higher than that of colon cancer. In 2017, the death rate of colon cancer in China was very close to that of esophageal cancer. However, the ASDR is lowest in esophageal cancer in Japan, compared with stomach cancer and colon cancer. The ASDR of Japan and India are almost at the same level among esophageal cancer, lower than that of stomach cancer and colon cancer. Besides, the trend of ASDR in the United States is opposite to that in China, and stomach cancer has a lower death. The standardized death rate of esophageal cancer in the United States is very high, and it has dropped from 20.53 per 100,000 in 1990 to 11.25 per 100,000 in 2017.
Table 1 shows the annual percentage change (APC) and average annual percent change (AAPC of three cancers death in China, Japan, the United States and India from 1990-2017. Joinpoint model showed that Esophageal cancer and stomach cancer death rate decreased rapidly from 2004 to 2007 This trend can be seen for stomach cancer, with overall AAPC values of -2.2%(-2.5,-2.0) in China, -2.8%(-3.1,-2.5) in Japan, -2.0%(-2.2,-1.8) in the U.S. and -1.4%(-1.7,-1.0) in India
The age, period, and cohort effects on colon cancer mortality
We analyzed the age, period, and cohort effects of colon cancer death rate in China, Japan, the United States, and India from 1992 to 2017 based on the APC model, and calculated RR values of age, period, and cohort. Finally, the results are shown in Figure 2 and Appendix 1. Regarding the age effect of colon cancer mortality, we set the age RR of colon cancer mortality in the 20-24 age group as 1. The RR of China is 63.92 in the 85-89 age group, and the RR of 85-89 age group in Japan is 180.17, and the RR value of the US in the 85-89 age group is 149.19, while the RR value of India in the 85-89 age group is 79.07. The RR values of the death rate of colon cancer in the four countries all increased monotonously with age. But generally speaking, the RR values of colon cancer mortality in Japan and the United States are higher than those of China and India in all age groups.
For the period RR of colon cancer mortality, we set the RR to 1 of colon cancer mortality in 1992. In 2017, the RR of China was 1.54, the RR of Japan was 1.70, the RR of United States was 1.73, and the RR of India was 2.23. From 1992 to 2017, the RR value of death rate in the four countries showed an overall upward trend, while the RR of colon cancer mortality in India showed a tortuous upward trend. For the cohort effect of colon cancer death rate, we set the RR of colon cancer to 1 in the birth cohort 1903-1907, the RR of China in 1993-2007 of the birth cohort was 0.34, and the RR of the United States was 0.14. The RR for India is 0.07. The RR of colon cancer death rate in the four countries showed a downward trend with the cohort, and China had a slight upward trend in 1948-1952.
The age, period, and cohort effects on esophageal mortality.
We analyzed esophageal death rate in China, Japan, the U.S., and India from 1992 to 2017 based on the APC model, and calculated RR values of the results are shown in Figure 3 and Appendix 2. The age effect in Japan increased approximately linearly with increasing age from 30 to 75 years and peaking at approximately 75 year. After 75 years of age, the age effect continued to decrease. The RR of the United States has the similar trend to Japan. Other two countries age RR increased all the time from 20 to 90 age group. The period effect in China decreased from 1997 to 2002, and thereafter generally increased until the year 2007. After 2008, the period effect decreased again. However, the period RRs in Japan, the United States and India has an upward trend from 1992 to 2017.
The cohort effect in China, Japan, the United States and India generally decreased from the 1910s to the 1990s. The cohort effect maintained a relatively stable trend before 1937 in China, Japan and the United States, which was followed by a decline. However, the cohort effect declined at an accelerated rate since the 1910s in Japan.
3.4 The age, period, and cohort effects on stomach mortality
We analyzed stomach death rate in China, Japan, the U.S., and India from 1992 to 2017 based on the APC model, and calculated RR values of the results are presented in Figure 4 and Appendix 3. The age effects for China, Japan, the United States and India showed that the death rate of stomach cancer had consistent increasing trends with age. In China and India, fluctuating period trends were presented in stomach cancer which showed a decreasing trend first during the period of 1992-2002 to 2007-2017; then the period effects increased rapidly from 2002 to 2007. However, stomach cancer as a whole showed an upward change in the United States. In Japan, the trend shows a decreased trend first from 1992 to 2012 and then increased from 2012 to 2017. The cohort effect death rate patterns of stomach cancer in four countries showing a decreasing trend (Figures 3-3). The cohort effect of stomach cancer peaked at around the year 1903 to 1907. The risk of stomach cancer related death was highest for those born in earlier birth cohort, but the later birth cohort of RR was lowest for four countries.
Forecast of the three cancers mortality trends using holt model
Figure 5 depicted the forecasts of the three cancers by Holt models during the period 1990–2027 for four countries. Overall trend showed an increase in colon cancer trends for the period from 2018 to 2027 in China, the U.S. and India. Whereas, the forecast trend of stomach cancer in China, Japan and India showed a slightly declined trend. However, it was also observed that the confidence interval of colon cancer for China was wider than Japan. This indicated more uncertainty during that period.