Assessment the association between liver cancer incidence and mortality rate with human development index in the European countries in 2012

Background: Liver Cancer (LC) is one of the most common cancers in the worldwide. This cancer is considered as the fifth most common cancer in male and the ninth most common cancer in female. However, socioeconomic factors and morbidity and mortality of cancer are linked by sophisticated and flexible pathways. We were investigated the association between incidence and mortality of LC with the Human Development Index (HDI) in European countries in 2012. Methods: This study was an ecologic study in European countries for assessment the correlation between Age-Specific Incidence Rate (ASIR) and Age-Specific Mortality Rate (ASMR) of LC with HDI and its details including: Life expectancy at birth, Mean years of schooling and Gross National Income (GNI) per capita. We used of Pearson correlation method for appraisement the association between HDI and its components with ASIR and ASMR. Data of study was analyzed by SPSS15 statistical analysis software; the significance level of the tests was considered P ˂ 0.05. Results: Generally in 2012, European countries have recorded 63,462 new cases of LC, crude rate was 8.6 and ASIR was 4.3 per 100,000. On the other hand in Europe countries in 2012, 62,191 cases of deaths were occurred due to LC, crude rate was 8.4 and ASMR was 3.9 per 100,000. Strong positive Correlation was observed between ASIR and ASMR (r = 0.848; P ≤ 0.001). HDI have weak negative correlation with ASIR of LC (r = - 0.194; P = 0.230), and strong negative correlation with ASMR of LC(r= - 0.515; P = 0.001). Conclusion: Increase in the human development index was associated with reduce in incidence and mortality of LC.


Introduction
Liver cancer (LC) is one of the most common cancers in the worldwide (Wei et al., 2014). This cancer is considered as the fifth most common cancer in male and the ninth most common cancer in female (Hall and Wild, 2003). Estimates from the year 2012 indicate that 782,451 new cases of LC occurred worldwide, including 554,369 cases in male and 228,082 cases in female. Also in this year, 745533 case of death of LC were observed in worldwide, including 521,041 cases in male and 224,492 cases in female (Ferlay et al., 2014). This tumor accounted for 5.6% of all human cancers (7.5% among male and 3.5% among female) in (Ferlay et al., 2001).
In the Europe, ASIR for LC in 2012 was equal to 4.3 per 100,000, with ranges from a relatively low rate in the Netherlands (ASIR=1.6) to the high rates in Republic of Moldova (ASIR=8.5). Also, Age Standardized Mortality Rate (ASMR per 100,000) for this cancer in the Europe in 2012 was 3.9 per 100,000, with ranges from a relatively low rate in Norway (ASMR=1.7) to the high rates in Republic of Moldova (ASMR=9.5) . LC is ordinarily a problem of the less developed countries (Ferlay et al., 2014). Extra than 85% of LC new cases take place in developing countries which do not have suitable detection and treatment services (Ferlay et al., 2010). LC is the second most common cause of mortality from cancer in worldwide, estimated to be responsible for closely 746,000 deaths in 2012 (9.1% of the whole death of cancer). The prognosis for LC is very low, so general ratio of LC mortality to incidence is around 0.95 (Ferlay et al., 2014).
Socioeconomic factors are connected with cancer incidence and mortality by intricate and variable pathways. One of the most important known meters of socioeconomic factors is Human Development Index (HDI). According to HDI, countries are assigned into four categories: countries with low HDI (HDI≤0.5), countries with Medium HDI (0.8> HDI>0.5), countries with high HDI (HDI≥0.8) and countries with very high HDI (HDI≥0.9) (Bray et al., 2012).
In the study that conducted in Asian countries about relationship of incidence and mortality of LC with HDI, negative correlation was observed between ASIR and ASMR with HDI, But this relationships wasn't significant . Similarly, relationship of HDI and incidence and mortality from other cancers were examined in other studies Hassanipour-Azgomi et al., 2016;Mohammadian et al., 2015;Pakzad et al., 2015a, b;Pakzad et al., 2016;Pakzad et al., 2015c;Rafiemanesh et al., 2015). However, according to our information, no study has been done still regarding the association between the ASIR and ASMR of LC with HDI in European countries; therefore in this study we investigate the association between incidence and mortality of LC with HDI in European countries in 2012.

Materials -Methods
This study was an ecologic study in European countries for appraisal the relationship among Age-Specific Incidence Rate (ASIR) and Age-Specific Mortality Rate (ASMR) with Human Development Index (HDI) and its details including: Life expectancy at birth, average years of schooling and Gross National Income (GNI) per capita. Data about the ASIR and ASMR for every European countries for year 2012 had gathered from GLOBOCAN project that is  (Ferlay et al., 2015). Also data about Human Development Index had extracted from Human Development Report 2013 (Malik, 2013).

Statistical analysis
In current report, we used of Pearson correlation method for assessment of correlation between Age-specific incidence rate and Age-specific mortality rate of LC by human development index and its details. All reported ASIR and ASMR were per 100,000. Statistical significance was considered as P<0.05. All P-values reported in study are two-sided. Also, Statistical analyses were performed using SPSS (Version 16.0, SPSS Inc.).

ASIR and HDI
The weak negative correlation was observed between the HDI and ASIR of

Discussion
Overall in 2012, European countries have recorded 63,462 cases of LC, Crude Rate was 8.6 and ASIR was 4.3 per 100,000. On the other hand in Europe countries in 2012, 62,191 cases of deaths occurred due to LC, Crude Rate was 8.4 and ASMR was 3.9 per 100,000. Correlation between ASIR and ASMR was 0.848 (P ≤ 0.001), that was statistically significant. In this study between HDI and ASIR of LC a negative correlation was seen about 0.194 (P=0.230), also between HDI and ASMR of LC was a negative correlation about 0.515 (P =0.001).
In European countries, Republic of Moldova (ASIR=8.5), Italy (ASIR=7.1), Luxembourg (ASIR=6.7), France (ASIR=6.6, and Spain (ASIR =5.9), had the maximum ASIR of LC. Four of these countries were in very high level of HDI, but Republic of Moldova was in Medium HDI level. In contrast, five countries with the lowest ASIR of the LC were The Netherlands (ASIR= 1.6), Iceland (ASIR= 1.7), Norway (ASIR=2.1), Belarus (ASIR=2.1), and Ukraine (ASIR=2.1), respectively (Ferlay et al., 2015). The HDI in three countries were in very high level of HDI, but in two countries were in high level of HDI (Malik, 2013).The results of study that conducted with Chang and et al,. displayed that hepatocellular carcinoma by reason of chronic hepatitis B infection was common in countries with low and medium level of HDI, mostly in Asian and African countries (Chang et al., 1997). However, the increased incidence of hepatocellular carcinoma in developed countries was mainly due to increase the prevalence of alcohol use and hepatitis C infection. It seems that the rise of HCC in western countries that have a higher HDI, has been due to hepatitis C infection and alcohol consumption (Liver, 2012). However, ASIR of LC in Europe in 2012 was 6.8 per 100,000 that was less than observed ASIR in the world (ASIR=15.3), Africa (ASIR=12.4), Asia (ASIR =20) and Oceania (ASIR=7.8) (Ferlay et al., 2015). In developing parts of the world, especially in Asian countries, cancer is becoming one of the most severe health problems. So that in some of these countries, such as Japan and South Korea, cancer is known as one of the most common causes of deaths. It is expected that if current management strategies and programs do not modified, the number of deaths from cancer by 2020 in these areas will reach 7.1 million cases per year (Mackay, 2006).
The distribution of cancers in different parts of the world in terms of human development index is very different, so in regions with very high, high, medium and low HDI, various cancers are classified as the most common cancer. cancer of the lung, breast, colorectal and prostate in areas with very high and high HDI are considered as the most common cancers that almost include half of new cancer cases in this region. Also, in regions with medium and low HDI, in addition to breast, colorectal and lung cancer, cervical cancer, liver and stomach cancer classified as cancers with high incidence and mortality. However, in regions with low HDI, cancers due to infectious agents included a large part of incidence and mortality of cancer (Bray et al., 2012;Franceschi and Wild, 2013 This study is an ecological study and its results can be interpreted only at the population level and attribution of the results of this study to individual levels lead to occurrence of ecological fallacy. This study also has some advantages. The first advantage is that we studied all European countries. So the data have perfect integrity. The second advantage is the novelty of findings because we couldn't find a study that shows relationship between the ASIR and ASMR of LC with HDI and its components in European countries. Therefore, it is proposed that similar studies in other parts of the word should be done, so that the relationship hypothesis between the incidence and mortality rate of LC and HDI in these regions can be examined.

Conclusion
Correlation between ASIR and ASMR was statistically significant. Also, we were observed a negative correlation between HDI and the ASIR of LC, but between the HDI and ASMR of LC significant correlation was observed. Therefore, increase in the human development index was associated with reduce in incidence and mortality of LC.