Global cancer transitions according to the Human Development Index (2008–2030): a population-based study

Summary

Background

Cancer is set to become a major cause of morbidity and mortality in the coming decades in every region of the world. We aimed to assess the changing patterns of cancer according to varying levels of human development.

Methods

We used four levels (low, medium, high, and very high) of the Human Development Index (HDI), a composite indicator of life expectancy, education, and gross domestic product per head, to highlight cancer-specific patterns in 2008 (on the basis of GLOBOCAN estimates) and trends 1988–2002 (on the basis of the series in Cancer Incidence in Five Continents), and to produce future burden scenario for 2030 according to projected demographic changes alone and trends-based changes for selected cancer sites.

Findings

In the highest HDI regions in 2008, cancers of the female breast, lung, colorectum, and prostate accounted for half the overall cancer burden, whereas in medium HDI regions, cancers of the oesophagus, stomach, and liver were also common, and together these seven cancers comprised 62% of the total cancer burden in medium to very high HDI areas. In low HDI regions, cervical cancer was more common than both breast cancer and liver cancer. Nine different cancers were the most commonly diagnosed in men across 184 countries, with cancers of the prostate, lung, and liver being the most common. Breast and cervical cancers were the most common in women. In medium HDI and high HDI settings, decreases in cervical and stomach cancer incidence seem to be offset by increases in the incidence of cancers of the female breast, prostate, and colorectum. If the cancer-specific and sex-specific trends estimated in this study continue, we predict an increase in the incidence of all-cancer cases from 12·7 million new cases in 2008 to 22·2 million by 2030.

Interpretation

Our findings suggest that rapid societal and economic transition in many countries means that any reductions in infection-related cancers are offset by an increasing number of new cases that are more associated with reproductive, dietary, and hormonal factors. Targeted interventions can lead to a decrease in the projected increases in cancer burden through effective primary prevention strategies, alongside the implementation of vaccination, early detection, and effective treatment programmes.

Funding

None.

Introduction

Global action is needed to stem the increasing burden of non-communicable diseases, especially in low-income and middle-income countries1, 2, 3, 4, 5, 6, 7, 8, 9 which now bear 80% of the worldwide burden of such diseases.¹⁰ Cancer, already the leading cause of death in many high-income countries, is set to become a major cause of morbidity and mortality in the next few decades in every region of the world, irrespective of level of resource.10, 11, 12

The UN has forecast that the global population will reach 7 billion by 2012 and 8·3 billion by 2030.¹³ The effect of population ageing and growth will be greatest in low-income and middle-income countries. These changes translate to a predicted global burden of 20·3 million new cancer cases by 2030 compared with an estimated 12·7 million cases in 2008, and a predicted 13·2 million cancer-related deaths worldwide by 2030, up from 7·6 million in 2008.¹¹ Such a demographic transition and the resulting upsurge in cancer incidence and mortality are contingent on population projections that assume decreases in human fertility and population growth as a result of continuous social and economic development,¹⁴ and on incidence and mortality rates of all cancer types combined remaining unaltered over the next few decades.

The static trends in the risk of cancer in future decades seems the less robust of these two assumptions, especially in view of the cancer-specific incidence and mortality trends seen over the past half century. Rather than describing constant rates over time, many reports have documented lagged changes in lung and other tobacco-related cancers according to the country-specific and sex-specific phases of the tobacco epidemic, uniform decreases in stomach cancer as a result of primary prevention efforts, and a rising incidence of breast, colorectal, and prostate cancers, initially in affluent populations and, within the last couple of decades, in historically less-affluent populations at lower cancer risk. The changes are likely to be attributable to a combination of unfavourable changes in several ill defined reproductive, dietary, metabolic, hormonal, and other behavioural determinants that increase the risk of these cancers. The so-called cancer transition—an analogy to Omran's epidemiological transition¹⁵—thus fits well with the occurrence of socioeconomic transition in several historically low-resource to medium-resource populations. The result has been a reduction in the prevalence of predominantly infection-based diseases, and a concomitant rise in those with apparently little or no established associations with infection.¹⁶

By linking geographical and temporal patterns of cancer to corresponding levels of social and economic progress, we provide an overview of the key characteristics of the global cancer transition. We used the Human Development Index (HDI)¹⁷ as an indicator of socioeconomic development, and rates of cancer incidence and mortality as markers of the extent of the cancer transition globally. We aimed to draw attention to geographical variations and trends in cancer-specific rates in each of the HDI areas and in different world regions, and to offer a global, trends-based profile of the possible cancer burden in 2030.