Primary liver cancer has unique geographical distribution and predisposing viral infection etiologies, which comprises HCC and ICC. HCC is the most common type, with hepatitis B, hepatitis C, alcohol use, and preexisting liver cirrhosis being the most important risk factors1. Furthermore, the incidence of HCC generally follows the geographical distribution of hepatitis B, hepatitis C virus, liver cirrhosis, and increasing prevalence among patients with nonalcoholic fatty liver disease2. This indicates that a region with risk factors for HCC would be the region with a high incidence of primary liver cancer. Although HCC typically occurs in adults, 0.5%-1% of cases are reported to occur in patients less than 20 years old3. It is the second most common (20%) primary liver malignancy in adolescents and most commonly affects children between 10 to 19 years old4. Specifically, children in Asian countries are 10 times more likely than children1 in North America to perinatally acquire hepatitis B infection5. Although treatments for liver cancer have improved gradually, primary liver cancer is still one of the leading causes of cancer death annually6.
In order to elucidate the associations between incidence/mortality of liver cancer and development within countries, we considered whether HDI, CHE per capita, and CHE/GDP influence the incidence numbers, mortality numbers, MIRs, and 𝛿MIR of liver cancer worldwide.
Countries with higher development and health expenditures have higher incidence rates, and this statistic is possibly due to the wide implementation of early cancer screening systems7. The higher the HDI, current health expenditure, and CHE/GDP are, the higher the incidence of crude rate will be (p < 0.001, p < 0.001, p = 0.002 Fig. 1A, 1C, 1E respectively).
On the contrary, countries with higher HDI, CHE per capita and CHE/GDP have lower mortality rates (p < 0.001, p < 0.001, p = 0.004 Fig. 1B, 1D, 1F respectively). This suggests that a country may have a better health care system, which results in an increased elderly population and increased incidence and mortality rates in cancer patients8. Therefore, MIR—which is a practical indicator for the evaluation of cancer care—is inversely proportional to HDI, CHE per capita, and CHE/GDP based on our analysis (Fig. 2).
Additionally, there are significant associations between 𝛿MIR and HDI as well as CHE per capita (Fig. 3A and 3B). However, the 𝛿MIR had no significant correlation with CHE/GDP (Fig. 3C). This indicates that a country with higher CHE/GDP does not affect the outcomes of 𝛿MIR for liver cancer in years. It is worth to note that valuables of 𝛿MIR result from the difference between valuables in 2012 and those in 2018 in each country.
There are some limitations in our study. For example, our results were calculated from the WHO database and any errors in the primary data would have influenced our secondary database study. Secondly, the use of the HDI, CHE per capita, and CHE/GDP to represent the healthcare disparities would be a major limitation itself. In future studies, other additional factors should be investigated.
We evidenced that favorable liver cancer 𝛿MIRs are not associated with CHE/GDP, although it has a significant relationship with HDI and CHE per capita. This result is worth the attention of the public health system all over the world.