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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 11  |  Issue : 2  |  Page : 88-97

Worldwide incidence and mortality of bladder cancer and human development index: An ecological study


1 Social Determinants of Health Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran
2 Department of Public Health, School of Medicine, Dezful University of Medical Sciences, Dezful, Iran
3 Social Determinants of Health Research Center, School of Allied Medical Sciences, Shahrekord University of Medical Sciences, Shahrekord, Iran

Date of Submission28-Jun-2019
Date of Decision27-Sep-2019
Date of Acceptance06-Dec-2019
Date of Web Publication29-Jan-2020

Correspondence Address:
Mr. Zaher Khazaei
Department of Public Health, Iranian Research Center on Healthy Aging, Sabzevar University of Medical Sciences, Sabzevar
Iran
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/INJMS.INJMS_108_19

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  Abstract 


Background and Objective: Bladder cancer (BC) is the most common cancer of the urinary and genital tract. Many factors, including environmental and socioeconomic factors, also affect the incidence and mortality of BC. The aim of this study was to evaluate the epidemiology of BC incidence and mortality worldwide based on the data extracted in 2018. Materials and Methods: The present study is a descriptive-analytic study that extracts the incidence and mortality rates of cancer from the World Bank in 2018. The incidence and mortality rates and BC distribution maps were drawn for world countries. To analyze data, correlation test and regression tests were used to evaluate the correlation between the incidence and mortality with the Human Development Index (HDI). The statistical analysis was carried out by Stata-14 and the significance level was estimated at the level of 0.05. Results: The results showed a positive and statistically significant correlation between the incidence (r = 0.587, P < 0.0001) and mortality (r = 0.271, P < 0.001) of BC with the HDI index. The results showed that there was a positive correlation between the incidence of BC with Gross national income per 1000 capita (GNI) (r = 0.405, P < 0.001), mean years of schooling (MYS) (r = 0.525, P < 0.001), life expectancy at birth (LEB) (r = 0.566, P < 0.001), and expected years of schooling (EYS) (r = 0.574, P < 0.001). In addition, there was a positive and statistically significant correlation between mortality rate with GNI/1000 capita (r = 0.186, P < 0.01), MYS (r = 0.227, P < 0.01), LEB (r = 0.305, P < 0.01), and EYS (r = 0.250, P < 0.01). Conclusion: Given that the incidence and mortality of BC in high-HDI countries is higher, more research in these countries is needed to identify the factors affecting the incidence of disease in these countries. We can perform prophylactic actions to prevent the incidence and mortality of this cancer by identifying the risk factors of the aforementioned disease.

Keywords: Bladder cancer, Human Development Index, incidence, mortality, world


How to cite this article:
Goodarzi E, Sohrabivafa M, Dehkordi AH, Khazaei Z. Worldwide incidence and mortality of bladder cancer and human development index: An ecological study. Indian J Med Spec 2020;11:88-97

How to cite this URL:
Goodarzi E, Sohrabivafa M, Dehkordi AH, Khazaei Z. Worldwide incidence and mortality of bladder cancer and human development index: An ecological study. Indian J Med Spec [serial online] 2020 [cited 2020 Aug 13];11:88-97. Available from: http://www.ijms.in/text.asp?2020/11/2/88/277238




  Introduction Top


Nowadays, noncommunicable diseases are the leading cause of death in the world. In recent years, cancer control has been a major challenge for public health. Urbanization, population aging, and increased life expectancy have led to major changes in population structure and increased burden of noninvasive diseases, including cancers.[1],[2],[3] Cancer is the leading cause of death in some developed countries and the second leading cause of death after cardiovascular disease in underdeveloping countries.[4],[5] Bladder cancer (BC) is the most common cancer of the urinary and genital tract.[5],[6],[7] According to the GLOBOCAN report in 2008, this is the ninth common cancer, the 11th most prevalent cancer, and the 14th leading cause of cancer deaths in the world. Some 430,000 new cases of this cancer were detected in 2012.[4],[8] This type of cancer is considered one of the most important ones as it impacts the quality of life of patients and their economic costs and mortality.[8]

The most important factors affecting the incidence of BC are lifestyle changes; the prevalence of Schistosoma hematobium parasite in some areas, such as Africa; and exposure to chemicals in the workplace. Environmental and socioeconomic factors are also effective in mortality from BC.[8] The general trend of the incidence and death of BC can be seen in all parts of the world and in all layers of economic development. The difference in the incidence of BC in the world is not solely due to its causative factors, but also due to differences in the cancer registration system in different countries.[4],[6] Annually, around 900,000 new cases of this cancer occur and about 250,000 deaths occur due to BC worldwide.

Men are 3–4 times more likely to be infected than women, and their prevalence is in the sixth decade of life. The peak in BC is in the seventh and eighth decades of life, therefore it was considered an elderly disease.[9] In 2012, 118,000 new cases and 52,000 deaths were estimated in Europe.[9] The incidence and mortality rate in the Western and developed countries has been decreasing, but it is rising in developing countries and Eastern Europe.[10] One-third of new cases of BC occur in developing countries.[6]

BC deaths have fallen in developed countries sharply over the past half century. The socioeconomic status is effective in the incidence and survival of BC. The survival of this cancer is very low in patients with low socioeconomic status. The incidence of BC in developing countries is increasing and the burden of the disease is increasing as well.[6] In addition, according to the UN estimates in the 1990s, in relation to the Human Development Index (HDI), in areas with high HDI, the burden of diseases caused by BC is higher. The HDI is a summary of human development measurements. This indicator measures the average achievement in a country in three main dimensions of human development, including long and healthy life, knowledge acquisition, and appropriate living standards.[11]

Considering the global pattern of BC and its timing in recent years, awareness of this cancer is necessary to plan and manage financial and human resources to prevent it. In spite of the increasing burden of cancer in developing countries, only 5% of global resources have been spent on developing countries.[12] It is necessary for each country to achieve a single result by comparing its data with other countries on whether the socioeconomic status has an impact on the risk factors for cancer incidence or not.

The purpose of this study is to assess the impact of socioeconomic development (based on the HDI) on the global trend of BC incidence and deaths in the world based on data available at the GLOBOCAN in 2018. In this study, we intended to study the key characteristics of BC in the world by examining the relationship between the incidence rate and the HDI, which consists of life expectancy, education, and GNI.


  Materials and Methods Top


Incidence

The methods used to calculate the incidence associated with gender and age in each country, in order of priority, fall into the following broad categories: (1) the reported national incidence rate was announced by 2018 (45 countries); (2) the most recent observed (national or regional) rates were applied to the population in 2018 (50 countries); (3) the rates were calculated using national mortality data with modeling, as well as the mortality and morbidity ratio of the cancer record in that country (14 countries); (4) the rates were calculated using national mortality using modeling, death rate, and incidence of cancer recording in neighboring countries (37 countries); (5) the national incidence rates for age and sex for all cancers were obtained by averaging the overall rates of neighboring countries. Subsequently, these rates were cumulative to produce a national incidence for each specific site using the relative frequency of cancer data (7 countries); and (6) rates were calculated as the average of the neighboring countries.

Mortality

The methods used to calculate mortality rates associated with genital and age-related cancer in each country, in priority order, are categorized in the following general categories: (1) the nationally monitored mortality rate was announced by 2018 (81 countries); (2) the latest national mortality rates observed for the population in 2018 (20 countries); (3) rates were calculated using data from the modeling assistance model, as well as the proportion of deaths to the prevalence of cancer reporting in neighboring countries (81 countries); and (4) rates were calculated as the average of the neighboring countries (3 countries).[13],[14]

Human Development Index

The HDI is a composite index of the following three-dimensional indicators: life expectancy, study rates, and mastery of the resources needed to have a decent life. All the groups and regions that have made significant progress on all components of HDI have grown faster than those with low or moderate HDIs. As the indicator shows, the universe is unequal as national averages do not show different experiences of people's lives. There are many inequalities in the northern and southern countries and income inequalities have increased in each country and between countries.[15],[16],[17]

Statistical analysis

In this study, the correlation bivariate method was used to assess the correlation between the incidence and mortality rates of BC and the HDI. Linear regression models were also used to assess the HDI effect on the incidence rate of BC. Statistical significance level was considered lower than 0.05. Data analysis was conducted by Stata 14 Softwar version (Texas, USA).


  Results Top


According to the results of cancer recordings in 2018, 18,078,957 cases of cancer were recorded in both sexes, of which 549,393 (3.2% of all cancers) were related to BC. The highest incidence of BC in the Asia continent was with 198,753 cases (36.2%) and the lowest incidence was related to the Oceania continent with 3794 cases (0.69%). The number of deaths due to the total number of cancer cases in 2018 was 9,555,027, of which 199,922 cases (25.2%) are related to BC. The highest mortality rate was on the continent of Asia with 84,669 cases (42.4%), and the lowest mortality rate was on the Oceania continent with 1824 cases (0.91%) [Figure 1].
Figure 1: Incidence and mortality rates bladder cancer by continents in 2018 [Source: GLOBOCAN 2018]

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[Table 1] shows the incidence and mortality rate of BC in different countries. The results of the study showed that the highest incidence of BC was found in Lebanon (25 in 100,000), Greece (21.2 in 100,000), and Denmark (17.9 in 100,000), with the highest mortality rates in the Lebanon countries (3.9/100,000), Egypt (6.6/100,000), and Syrian Arab Republic (6.1/100,000) [Table 1] and [Figure 2].
Table 1: Estimated age-standardized incidence and mortality rates of bladder cancer across both sexes and all ages in the world in 2018

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Figure 2: Estimated age-standardized incidence and mortality rates of bladder cancer across both sexes and all ages (world) in 2018 [Source: GLOBOCAN 2018]. (a) Incidence rate. (b) Mortality rate

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Based on the reported cancer incidence rates in 2018, the highest incidence (10.5% in 1,000,000) and mortality (2.5 in 100,000) of BC are due to very high HDI areas [Figure 3].
Figure 3: Distribution of bladder cancer by Human Development Index

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The results of analysis of variance showed that the highest mean incidence (9.7 out of 100,000) of BC was related to very high human development and the lowest mean incidence (2.4/100,000) was related to low human development, and this difference was statistically significant (P < 0.0001). The lowest mortality rate (1.5 out of 100,000) was related to medium human development and the highest mortality (2.6 out of 100,000) was related to very high human development, and this difference was statistically significant (P < 0.0001) [Table 2].
Table 2: Bladder cancer incidence and mortality in different Human Development Index regions in 2018

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The results showed a positive and statistically significant correlation between incidence (r = 0.587, P < 0.0001) and mortality (r = 0.271, P < 0.001) of BC with HDI index [Figure 4].
Figure 4: Correlation between the Human Development Index and incidence and mortality rates of bladder cancer in the world in 2018. R-squared linear = 0.587,P <0.001, R-squared linear=0.271, P < 0.001

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The results showed a positive correlation between the incidence of BC with GNI (r = 0.405, P < 0.001), MYS (r = 0.525, P < 0.001), LEB (r = 0.566, P < 0.001), and EYS (r = 0.574, P < 0.001). The results also showed a positive and statistically significant correlation between mortality rate with GNI (r = 0.186, P < 0.01), MYS (r = 0.227, P < 0.01), LEB (r = 0.305, P < 0.01), and EYS (r = 0.250, P < 0.01) [Table 3].
Table 3: Pearson's correlation between Human Development Index component and dependent variable

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  Discussion Top


BC is one of the rare, but relatively fatal, cancers.[6] The incidence of this cancer in men is higher than that of women, which may be due to exposure to men with risk factors affecting the disease. The results of this study showed that the highest incidence of BC in Asia was in Lebanon (25/100,000). In other high-incidence countries, the incidence was 21.2/100,000 in Greece and 17.9/100,000 in Denmark. The highest mortality rates for BC were in Lebanon (9.3% in 100,000), Egypt (6.6 in 100,000), and Syrian Arab Republic (6.1 in 100,000). In general, the incidence of BC is the highest in Asia (36.2%). Other regions are the European continent (35.9%), North America (16.7%), Latin America (5.3%), Africa (5.3%), and Oceania (0.69%). The lowest incidence was reported in the Oceania region.

Nearly 430,000 new cases of BC were estimated in 2012. Nearly 60% of the new cases of BC and half of the deaths occurred in less developed countries.[18] In 2012, BC rate in Europe, the Middle East, and the United States was 18, 17.2, and 12.9/100,000, respectively. The most important factor in the geographic difference in the incidence and mortality in the world is the difference in the prevalence of smoking and hematobium infection.[19]

In Egypt, BC accounts for 30% of all cancers. The high incidence of BC in Egypt and North Africa could be due to its proximity to the Delta region and the prevalence of hematobium infection in these areas extensively.[19]

Differences in the incidence of cancer in these areas can be due to differences in the socioeconomic status of individuals. One of the indicators of the status of countries is the HDI. This indicator examines the position of a country in three main aspects of development including life expectancy, knowledge, and living standards. Lifespan is evaluated by life expectancy at birth, knowledge with years of potential education, and living standards proportional to per capita income or gross domestic product. In countries with high levels of HDI, the incidence and mortality rate of BC is higher.[6]

Differences in health-care systems, protocols, or access to diagnostic and treatment facilities, especially between countries at different levels of human development, can partly explain the observed differences in BC survival rates and mortality rates.[20],[21]

The highest incidence of BC in men and women was reported in Europe, the United States, sub-Saharan Africa, Asia, and South America. Most deaths are in parts of Europe and North Africa and the lowest in Asia, Central America, and Central Asia. The incidence and death rate of this cancer in the Western countries has declined. However, it is increasing in some European countries as well as developing countries of Asia.[8] In countries such as Ireland and Iceland, the trend has been steady, and in Spain, the incidence has risen in men, but has declined in women.[4]

The results of the study by Pakzad et al. showed that the highest incidence of BC was in the Republic of Korea, Mongolia, Japan, China, and Tajikistan. These countries had a high and medium HDI. In this study, a strong correlation was found between HDI (income level) and BC.[6] In a study by Mahdavifar et al. 2016, the highest incidence of BC was observed in Belgium, Lebanon, Malta, Turkey, and Denmark, with a strong link between HDI and BC. It also shown that there was a significant difference between countries with high and low HDI, but there was little difference in mortality.[8]

In a study by Wong et al. 2018, there was a significant positive correlation between HDI incidence and BC. The findings of this study were similar to the results of the current study.[9] These studies indicate that cancer is still a global issue of concern to health-care providers and requires more extensive studies to understand the link between economic development and BC. Socioeconomic changes have had a significant impact on the incidence and severity of cancer. In countries with low or average incomes, the risk of cancer is increasing. The cancer-causing infections account for about 26% of cancers in low- and middle-income countries. Smoking, chemical exposure, diet, environmental contamination, and genetic predisposition are BC risk factors.[8],[22] BC is associated with the industrialization of communities, and figures indicate that most deaths from this cancer occurred in developed countries.

In industrialized countries, exposure to aromatic amines and other chemicals in painting workers of buildings and rubber or aluminium industrial workers and other occupational exposures have been the underlying causes of increasing incidence of cancer in these countries. On the other hand, advances in treatment and early detection of disease may increase the survival of patients and reduce mortality.[18],[23]

The results of this study showed that there was a positive correlation between HDI and BC incidence (r = 0.587, P < 0.0001) and death of BC (r = 0.271, P < 0.001) in 2018. The study also found that the reasons for the increased incidence of BC in higher HDI countries include the availability of appropriate infrastructure, treatment protocols, advanced diagnostic methods, favorable access to primary health services, and timely screening. The cause of higher mortality in developing countries is the lack of access to appropriate diagnostic and therapeutic facilities, population aging, smoking, and physical inactivity. HDI is the average of geometric development of normal indices that measure the success of each dimension (ideal life, knowledge, and longevity). The goals of this indicator are beyond income and material to assess the long-term satisfaction of life for individuals in different societies. Indeed, paying attention to the human development was considered the real aim of the development program. Ultimately, it could provide a favorable opportunity for a healthy, creative, and happy life. Important factors for BC in most countries are smoking, lifestyle changes, and aging. It is possible to take effective steps to reduce the incidence of this disease and many chronic and noncommunicable diseases by presenting primary prevention strategies for BC, such as reducing tobacco usage and achieving normal body mass index. In spite of the relationship between these factors, the interpretation of such studies should be done with caution; on paying attention to the risk factors for the epidemiology of BC, the inherent constraints of ecological studies should be considered. In summary, the incidence and mortality rate of BC has increased in many countries. Providing early prevention methods and conducting epidemiological studies and implementing timely treatment and follow-up of BC patients, especially for the less developed countries, can be effective in reducing the burden of disease and improving the health system of the countries.


  Conclusion Top


Given that the incidence and mortality of BC in countries with high HDI is higher, paying attention to risk factors in these countries can be effective in reducing the incidence and mortality of the disease. Further studies to understand the risk factors associated with this cancer in countries with high levels of HDI can contribute to strategies for preventing this cancer.

Acknowledgments

The authors gratefully acknowledge many of the cancer registries worldwide and their staff for their willingness to contribute their data to this study.

Financial support and sponsorship

This study was financially supported by Kerman University of Medical Sciences, Kerman, Iran.

Conflicts of interest

There are no conflicts of interest.



 
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