International Trends in Prostate Cancer

The world population climbed over 7 billion in 2011. Over the next 40 years, the predicted growth in population will almost all come from the less-developed world. This is due to its higher birth rate and younger current population compared to those in the more developed world. The world population will continue to change at an exponential rate; in particular, the more developed world will account for a decreasing percentage of the total population. These facts are particularly important to keep in mind when investigating global trends in prostate cancer. In 2012 there were 1,111,689 new diagnoses of prostate cancer worldwide as well as 307,471 deaths. There is a tendency to forget that almost all literature on prostate cancer comes from the developed world, which can skew our perception of the disease. Prostate cancer is often described as a disease of the developed world, a fact confirmed by its higher incidence rates. However, of the 307,471 deaths from prostate cancer reported in 2012, over 50% occurred outside of the United States and Europe. These numbers will only get higher, hence, it is extremely important for us to further understand the population trends in prostate cancer not just the United States but throughout the world. This chapter aims to provide up-to-date information on prostate cancer incidence and mortality along with epidemiological changes in the disease, specifically from countries outside the United States.

Gathering global statistics on prostate cancer is not without difficulty. Different countries report data in different forms using different types of methodology. Databases are only as viable as the funding that supported them; therefore, the comparative accuracy of the statistics of more developed nations and those of their less developed counterparts needs to be taken into account.

The World Health Organization’s International Agency for Research on Cancer (IACR) publishes the incidence, mortality, and prevalence rates for all cancers. Known as GLOBOCAN, the IACR project publishes results on a periodic basis, with the latest update released in 2012. A total of 184 countries throughout the world have data collected, and for statistical purposes, a distinction is made between “more developed” and “less developed” regions. The more developed regions include all regions of Europe plus Northern America, Australia/New Zealand, and Japan. The less developed regions consist of all regions of Africa, Asia (excluding Japan), Latin America and the Caribbean, Melanesia, Micronesia, and Polynesia. This is the source of data used for comparison of rates between countries. It is however very difficult to compare global rates over time against each other; one of the disclaimers of GLOBOCAN is that comparison should not be performed between years as significant changes may be more due to methodology change rather than actual trends.

Incidence rates of prostate cancer

Globally, there were 1,111,689 new cases of prostate cancer diagnosed in 2012. Table 15.1 outlines these rates broken down by economic and geographic groupings. The most striking statistic is the massive difference between countries’ incidence rates. Of particular interest is the nearly five-times-higher incidence rates in the more developed regions over those in the less developed ones. However, even among less developed regions, there is a stark difference in incidence rates. In Southeast Asia the incidence rate of 5.5/100,000 is ten times lower than South America’s rate of 75/100,000. Figure 15.1 shows pictorially the incidence rates for countries measured by age-adjusted standardized rates per 100,000 population. Age-adjusted standardized rates supposedly attempt to limit the confounding effect of an aging population, thus increasing the amount of prostate cancer incidence. The reason for the marked difference in incidence rates between countries is likely to be multifactorial. These factors are likely to include genetic and lifestyle differences between populations along with differences in prostate cancer screening and treatment standards.

Table 15.1

Incidence Rates of Prostate Cancer Broken Down by Geographic and Socioeconomic Regions

Source: Ferlay et al.

Population	Numbers	Crude rate	ASR (W)	Cumulative risk
World	1,111,689	31.2	31.1	3.84
More developed regions	758,739	125.2	69.5	8.84
Less developed regions	352,950	12	14.5	1.65
Very high human development	750,896	131.9	73.7	9.34
High human development	195,839	38.2	37.5	4.55
Medium human development	115,942	6.4	7	0.72
Low human development	47,809	7.3	14.9	1.84
WHO Africa region (AFRO)	51,689	11.8	26.8	3.24
WHO Americas region (PAHO)	412,739	87.6	75	9.35
WHO East Mediterranean region (EMRO)	18,585	5.8	9.7	1.13
WHO Europe region (EURO)	436,688	99.9	60.9	7.82
WHO South-East Asia region (SEARO)	38,515	4.1	5.5	0.62
WHO Western Pacific region (WPRO)	153,167	16.2	12.6	1.37
IARC membership (24 countries)	807,515	61.5	51.3	6.49
Middle-East and Northern Africa (MENA)	29,377	12.9	19.7	2.38
Africa	59,493	11.1	23.2	2.81
Sub-Saharan Africa	51,945	12	27.9	3.37
Eastern Africa	17,187	9.8	23.3	2.82

The comparison between nations is important, but just as crucial is the change in incidence rates over time within populations. This on a global scale is difficult to assess due to changes potentially being caused by methodology/reporting changes rather than by actual disease changes. Therefore, only robust databases that have not altered over time can be used for this analysis. Center et al. analyzed 40 different countries worldwide and compared prostate cancer incidence rates over a 5-year period. Results showed that the incidence rate in 32 of the 40 countries had increased in the last 5 years. In particular, large increases were noted in Lithuania, China, and South Korea. This has been linked directly to an increase in the amount of PSA screening in these populations. The countries with stable incidence rates of prostate cancer are from the more developed world where large percentages of the population have already had PSA screening for a longer time period; such nations include Australia, New Zealand, and the United States.