Incidence and mortality of kidney cancers, and human development index in Asia; a matter of concern

Background The incidence and mortality of kidney cancer have steadily increased by 2%- 3% per decade worldwide, and an increased risk of kidney cancer has been observed in many Asian countries. The information on the incidence and mortality of a disease and its distribution is essential for better planning for prevention and further studies. Objectives This study aimed to assess the incidence and mortality of kidney cancer and their correlation with the human development index (HDI) in Asia. Materials and Methods This ecological study was based on GLOBOCAN data Asia for assessment the correlation between age-specific incidence rate (ASIR) and age-specific mortality rate (ASMR) with HDI and its details that include life expectancy at birth, mean years of schooling and gross national income (GNI) per capita. We use of correlation bivariate method for assessment the correlation between ASIR and ASMR with HDI and its components. Results A total of 121 099 kidney cancer cases were recorded in Asian countries in 2012.Overall, 80 080 cases (66.12%) were males. Sex ratio was 1.95. The three countries with the highest number of new patients were china (66 466 cases), Japan (16 830 cases), India(9658 cases), respectively. Positive correlation were seen between HDI and ASIR of kidney cancer 0.655 (P = 0.001), and HDI and ASMR of kidney cancer 0.285 (P = 0.055). Conclusions A positive relationship between ASIR and the HDI was seen. The relationship is due to risk factors in countries with high development such as older age, smoking, hypertension, obesity, and diet. However, ASMR showed no significant relationship with HDI.

the fifth and sixth decades of their life, and one of the specific characteristics of the disease is asymptomatic (19,20,32). Deciding factors for diagnosis and treatment of patients with locally and advanced RCC are sex, race, the income level and social economic status, which influence the provider and the recipient of health care and decision-making on the disease (33). Studies showed that the incidence of kidney cancer is affected by economic and social disparities (18,19). It reflects the regional disparities in human development. To study the trend and its relationship with risk factors, the human development index (HDI) is useful. The index to classify cancer for globalization is beneficial because it considers education, life expectancy and the national income (34)(35)(36)(37). The assumption is that the populations of developing countries have higher mortality rates than the incidence compared with developed countries (38,39). After several decades of increasing trend in the incidence and mortality of kidney cancer, rates are stable, or are started to decrease in many Western countries (40). It seems it is due to reducing the prevalence of tobacco consumption, and improving health professional than decades ago because the prevalence of smoking is higher among people who live below the poverty line (31.5%) than those at the top of this level (19.6%) (7,40).

Objectives
The information on the incidence and mortality of a disease and its distribution in terms of geographical areas is essential for better planning for prevention and further studies. There is, probably, a relationship between the development and cancer incidence and mortality. Considering lack of a study to investigate kidney cancer incidence and deaths in Asia, this study aimed to assess the incidence and mortality of kidney cancer and their correlation with the HDI in Asia.

Materials and Methods
This study was an ecologic study in Asia for assessment of the correlation between age-specific incidence rate (ASIR) and age-specific mortality rate (ASMR) with HDI and its details that include mean years of schooling, life expectancy at birth and gross national income (GNI) per capita. Data about the ASIR and ASMR for every Asian country for the year 2012 get from global cancer project (http://globocan.iarc.fr/Default.aspx) (41). HDI extracted from Human Development Report 2013 included information about HDI and its details for every country in the word for year 2012 (42). Method of estimation of the age-specific incidence and mortality rates in the global cancer project by in-Journal of Nephropathology, Vol 6, No 1, January 2017 www.nephropathol.com 32 ternational agency for research on cancer is as follows:

Age-specific incidence rate
The methods of estimation are country specific and the quality of the estimation depends upon the quality and on the amount of the information available for each country. In theory, there are as many methods as countries, and because of the variety and the complexity of these methods, an overall quality score for the incidence and mortality estimates combined is almost impossible to establish. However, an alphanumeric scoring system, which independently describes the availability of incidence and mortality data, has been established at the country level. The combined score is presented together with the estimates for each country with an aim of providing a broad indication of the robustness of the estimation. More details about the GLOBOCAN project were previously published (4,43,44).

Age-specific mortality rate
Depending on the degree of detail and accuracy of the national mortality data, six methods have been utilized in the following order of priority: 1-Rates projected to 2012 (69 countries), 2) Most recent rates applied to 2012 population (26 countries), 3) Estimated as the weighted average of regional rates (1 country), 4) Estimated from national incidence estimates by modelling, using country-specific survival (2 countries), 5) Estimated from national incidence estimates using modelled survival (83 countries), 6) The rates are those of neighboring countries or registries in the same area (3 countries) (4,44,45).

Human development index
HDI, a composite measurement of indicators along three dimensions: life expectancy, educational attainment and command over the resources needed for a decent living. All groups and regions have seen notable improvement in all HDI components, with faster progress in low and medium HDI countries. On this basis, the world is becoming less unequal. Nevertheless, national averages hide large variations in human experience. Wide disparities remain within countries of both the North and the South, and income inequality within and between many countries has been rising (42).

Ethical issues
The research followed the tenets of the Declaration of Helsinki.

Statistical analysis
In this study, we use correlation of coefficient for assessment of the correlation between ASIR and ASMR with HDI and its details. All reported P values are two-sided, and statistical significance was assumed if P < 0.05. Statistical analyses were performed using SPSS (version 15.0, SPSS Inc.).

Results
A total of 121 099 kidney cancer cases were recorded in Asian countries in 2012. Overall, 80 080 cases (66.12%) were males and 41 019 cases (33.87%) females. Sex ratio in Asia was 1.95. The five countries with the highest number of new patients were china (66 466 cases), Japan (16 830 cases), India (9658 cases), Republic Korea (5651 cases), and Turkey (3992 cases), respectively. Among Asian countries, five countries with the highest standardized incidence rates of the cancer were Republic Korea with 8 per 100 000, Turkey with 5.6 per 100 000, Japan with 5.3 per 100 000, Singapore with 5.2 per 100 000, and Korea, Democratic Republic of 4.3 per 100 000, respectively. Five countries with the lowest standardized incidence rates of the cancer were Maldives with 0 per 100 000, Bhutan with 0.6 per 100000, Yemen with 0.6 per 100000, Bangladesh with 0.8 per 100 000, and Sri Lanka with 0.9 per 100 000, respectively. The number, crude and standardized incidence rates of the cancer in Asian countries based on sex are presented in Table 1. The countries with the highest and lowest ASIR in both sexes are observable in Table 1, Figure 1 and Figure 2. However, in 2012, in Asia, the number of deaths due to kidney cancer was 26 102 cases, 36 224 cases in men and 19 878 cases in women. The sex ratio (male to  female) of mortality was equal to 1.82. The five countries with the highest number of deaths were china (25 583 cases), Japan (8124 cases), India (5973 cases), Turkey (2656 cases), and Indonesia (2459 cases), respectively. The countries included a total of 44795 cases (89.78%) of the total mortality in Asia. In Asian countries, 5 countries with the highest standardized mortality rates from the cancer were Turkey with 3.8 per 100 000, Republic Korea 2.5 per 100 000, Palestine with 2.4 per 100 000, Syria with 2.3 per 100 000, and Iraq with 2.3 per 100 000, respectively. Five countries with the lowest standardized mortality rates from the cancer were Brunei with 0 per 100 000, Maldives with 0 per 100 000, Yemen with 0.5 per 100 000, India with 0.6 per 100 000, and Sri Lanka with 0.6 per 100 000, respectively. The number, crude, and standardized incidence rates of the cancer in Asian countries based on sex are presented in Table 2. The countries with the highest and lowest ASIR are observable in both sexes in Table 2, Figure  1 and Figure 4. In Table 3, amounts related to HDI and its components for each of the Asian countries (sorted based  on HDI) is shown. Accordingly, Asian countries are classified according to HDI as follows: three countries in the very high category, four countries in high, 35 countries in the middle category, three countries in low, and one in the unknown category.

ASIR and HDI
A positive correlation was seen between the ASIR of kidney cancer and HDI about 0.655. This association was statistically significant (P = 0.001). There was a positive correlation between the ASIR and life expectancy at birth about 0.558 (P = 0.001), positive correlation between the ASIR and mean years of schooling about 0.523 (P = 0.001), and positive correlation between the level of income per each person of the population and the ASIR equal to 0.409 (P = 0.005) ( Figure 3). In men, a positive correlation of 0.637 was observed between the ASIR of kidney cancer and HDI. It was statistically significant (P = 0.001). There was a positive correlation between the ASIR and life expectancy at birth about 0.539 (P = 0.001), positive correlation between mean years of schooling and the ASIR about 0.557 (P = 0.001), and positive correlation between the level of income per each person of the population and the ASIR equal to 0.366 (P = 0.012). In women, a positive correlation of 0.612 was observed between the ASIR of kidney cancer and HDI. It was statistically significant (P = 0.001). There was a positive correlation between the ASIR and life expectancy at birth about 0.509 (P = 0.001), positive correlation between mean years of schooling and the ASIR about 0.448 (P = 0.002), and positive correlation between the level of income per each person of the population and the ASIR equal to 0.347 (P = 0.018).

Discussion
Considering that close to 60% of the world's population live in Asia, paying attention to causes of incidence and mortality from the cancer is significant in the continent (46). Lifestyle changes in Asian countries could be predisposing factor for the cancer (47,48). In Asia, 56% of incidence cases, 62% of deaths, 70% of DALYs occurred in 2013 worldwide. In Asian countries, ASIRs of incidence, mortality, and 5-year prevalence of kidney cancer in this year were 2.8, 1.3, and 9.4, respectively (1). Kidney cancer incidence and mortality is different in various countries. This difference in incidence between countries is because of the accumulation of risk factors (49), including smoking, obesity, hyperten-sion, age, and diet in countries with high incidence. According to studies conducted in Asian countries, age-standardized incidence rates per 100 000 and the proportion of deaths to incidence per 100 000 were in Central and South Asia 1 and 0.7, in Southeast Asia, 1.9 and 0.68, in West Asia 2.3 and 0.62, and in East Asia 2.4 and 0.36, while in the United States 11.8 and 2.2. Given the under-reporting in developing countries (50), the United States with a HDI has mortality rates a declining trend, but in Asian countries the rates are stable or increasing. Based the results of the this study and other studies, incidence and mortality rates of all cancers are different in the world and in various socioeconomic levels due to early detection, improved access to health care, complex diagnostic imaging, and treatment availability. The incidence of kidney cancer has increased in many Asian countries, so that men, specifically in China, and Asian women in India have a significant increase. In a country like Singapore, trends in mortality have remained constant, but Japan has been a clear decline (46). In this study, the sex ratio (male to female) was 1.95, which is in line with other studies. This may be due to higher exposure to risk factors such as smoking and obesity (2,19,20,25,27,28,32). According to the findings of this study, the incidence of kidney cancer in Asia is related to the HDI. It seems that among Asian countries, the high incidence of kidney cancer has been associated with increasing HDI. It can be attributed to a decrease in other diseases and control of infectious diseases as well as aging in the countries. Aging is one of the most important risk factors for this cancer. According to statistics published by GLOBOCAN 2015, the cancer generally has increased between 1990 and 2013. In other words, the incidence rate for both sexes in terms of ASIR increased 23% (from 3.82 to 4.7), 34% in developing    (32,(51)(52)(53). Today, the average life expectancy for a child born in the United States is about 78 years, while a child in a country in Sub-Saharan Africa with an average life expectancy of between 39.6 to 65.9 years (33). Standard age distribution is various in different geographical areas. ASMR is similar to the ASIR, so that the highest in Europe and North America (3.1 and 2.6 per 100 000) and the lowest in Asia and Africa (0.6 and 1.5 per 100 000). With the increasing development of countries, aging of populations and reducing non-communicable diseases, rates of chronic disease such as cancer increasing. (54). Access to knowledge is another component. Our study found a positive correlation between the standardized incidence and the level of education. Also, in United States, in the lowest level of education in the population, kidney cancer mortality rate is 2.6 times higher than the highest level of education (55). It was shown that risk of kidney cancer in men is inversely related to higher education levels (56). In this study, there was a positive correlation between standardized incidence of the cancer and income levels per one in community. An ecological study has also reported that per capita daily intake of fat and protein is positively correlated with the incidence of kidney cancer in women and men (26). These findings are justified with aging (52) and an increase in cumulative effects of risk factors. The annual economic burden of kidney cancer in the United States in 2009 is estimated about $5.2 billion (43). About 85% of health care dollars is spent caring for kidney cancer inpatients (23). It can be concluded that the incidence of kidney cancer can also affect the HDI because it imposes economic costs on health systems and poverty in people (13).

Conclusions
The ASIR and ASMR of kidney cancer in countries with higher development is more. There was a positive and significant relationship between the ASIR of kidney cancer and HDI and HDI components (life expectancy at birth, the average years of schooling, and the level of income for each one of the country's population). The relationship is due to risk factors in countries with high development such as older age, smoking, hypertension, obesity, and diet. However there was a positive, but no significant relationship between the ASMR of kidney cancer and HDI and HDI components.

Limitations of the study
Our study was an ecological study and special limitations of this study include ecological misleading and lack of relation of group results with individuals.