Worldwide incidence of cancer could increase more than 75% by 2030, with the number of new cancer cases expected to double in the least developed countries, according to results of a population-based study.
Substantial increases in malignancies often associated with what researchers called a “Westernized” lifestyle — such as breast, prostate and colorectal cancers — will offset declines in cervical, stomach and other cancers in countries that have achieved higher levels of development or are transitioning toward it, the researchers wrote.
“Cancer is already the leading cause of death in many high-income countries and is set to become a major cause of morbidity and mortality in the next decades in every region of the world,” Freddie Bray, PhD, of the International Agency for Research on Cancer in Lyon, France, said in a press release. “This study serves as an important reference point in drawing attention to the need for global action to reduce the increasing burden of cancer.”
Bray and colleagues used GLOBOCAN, a database maintained by the International Agency for Research on Cancer, to obtain estimates of mortality and incidence from 27 types of cancers in 184 countries during 2008. They then linked country-specificestimates with each nation’s Human Development Index (HDI), a UN measure of socioeconomic development that takes life expectancy, adult literacy, education and standard of living into account.
The researchers examined patterns of cancer according to four predefined categories of socioeconomic development: low, medium, high and very high. They also examined incidence trends of seven common cancers — lung, breast, colorectal, stomach, prostate, liver and cervical cancers — from 1988 to 2002.
They used their findings to project how the cancer burden will change during the next 18 years, factoring in changing demographics.
“If 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,” Bray and colleagues wrote in the study. “The effect of population aging and growth will be greatest in low-income and middle-income countries.”
Countries with a low HDI — the majority of which are in sub-Saharan Africa — currently have high rates of cancers associated with infection, such as cervical cancer, stomach cancer, liver cancer and Kaposi’s sarcoma. Countries with higher HDI have higher rates of lung, prostate and colorectal cancers, which are associated with lifestyle factors such as smoking, obesity and diet.
Improved societal and economic conditions in countries that currently have a low HDI may translate into a decrease in infection-related cancers, the researchers said. However, those decreases likely will be offset by an increased incidence of cancers that are more often associated with higher HDI countries.
Countries that have HDI classified as “very high” — including the United States — already carry an unbalanced proportion of the worldwide cancer burden, the researchers said. An estimated 40% of the global cancer incidence occurs in those nations, although they account for only 15% of the world’s population.
“In the United States and other high HDI countries, we see relatively high current cancer rates, but rates that tend to be flattening or even declining,” Nathan Grey, MPH, national vice president of global health for the American Cancer Society and one of the researchers involved in the study, told HemOnc Today. “In the United States, the overall age-adjusted cancer mortality rate has been going down rather than up for a decade or longer. Yes, we have a significant cancer burden, but we have turned the corner and are starting to go in the right direction. The question for us is, how do we accelerate that process?”
The United States has made progress by implementing policies and interventions — such as tobacco control efforts — that have helped to lower its cancer mortality rate, Grey said. Still, the country continues to grapple with a number of challenges, including disparities in cancer prevention, screening and treatment.
“We need to see improvement in colorectal screening,” he said. “We need to see improvement in breast and cervical cancer screening, which is more common among middle-class and wealthy Americans. We must make sure less-affluent people have access to those screenings, as well.”
Incidence of prostate cancer and breast cancer appear to be increasing in countries that currently have medium, high or very high HDI, whereas incidence of stomach cancer and cervical cancer generally are declining in those nations, the researchers wrote.
“This study underscores the diversity of cancer as a worldwide occurrence and the extent to which the disease patterns vary from country to country,” Bray and colleagues wrote. “Classification of these populations by broad levels of human development does, however, draw attention to some of the key determinants of such variations, especially in countries rapidly transiting from lower to higher levels of human development.”
The researchers suggested targeted interventions such as vaccination programs, prevention strategies designed to reduce tobacco and alcohol consumption, anti-obesity efforts and initiatives to increase physical activity could substantially reduce the projected increase in global cancer burden.
“This study reveals the dynamic nature of cancer patterns in a given region of the world over time,” Christopher Wild, PhD, director of the International Agency for Research on Cancer, said in a press release. “Countries must take account of the specific challenges they will face and prioritize targeted interventions to combat the projected increases in cancer burden via effective primary prevention strategies, early detection and effective treatment programs.”
- Bray F. Lancet Oncol. 2012;doi:10.1016/S1470-2045(12)70211-5.
- The researchers report no relevant financial disclosures.