Cancer incidence predicted to increase 75 percent by 2030

The study, led by Dr Freddie Bray of the International Agency for Research on Cancer (IARC) in Lyon, France, is the first to examine how the current and future patterns of incidence and mortality of different types of cancer vary between countries with different levels of development, as measured by their Human Development Index (HDI).

Although incidence rates and the burden of some types of cancer (such as cervical cancer and stomach cancer) appear to be mainly declining in countries transitioning socially and economically towards higher levels of human development, the reduction is likely to be offset by a substantial increase in the types of cancer more associated with a so-called "Westernised" lifestyle, including breast, prostate, and colorectal cancer.

"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; this study serves as an important reference point in drawing attention to the need for global action to reduce the increasing burden of cancer", states Dr Bray.

The study used data from GLOBOCAN, a database compiled by the International Agency for Research on Cancer (IARC) comprising of estimates of cancer incidence and mortality in 2008 in 184 countries worldwide. The researchers describe how patterns of the most common types of cancer varied according to four levels of human development. These findings were then used to project how the cancer burden is likely to change by 2030 in light of predicted changes in population size and ageing, as well as the changing trends in incidence rates of six of the most common types of cancer in countries with medium, high and very high levels of HDI.

Countries with a low HDI (predominantly countries in sub-Saharan Africa) currently experience a high incidence of cancers associated with infection, particularly cervical cancer and, dependent on the region or country, liver cancer, stomach cancer and Kaposi's sarcoma. By contrast, countries with a higher HDI (such as the UK, Australia, Russia, and Brazil) have a greater burden of cancers more commonly associated with smoking (lung cancer), reproductive risk factors, obesity and diet (female breast, prostate, and colorectal cancer).

While increasing living standards in the coming decades in lower-HDI countries may lead to a decrease in the burden of some infection-related cancers, the authors warn that, irrespective of future developments, there may be a surge in the types of cancer which currently affect mainly higher-HDI countries. They predict that demographic changes as well as changing trends in cancer incidence rates could lead to a large increase in the cancer burden in lower or medium HDI countries, with medium HDI countries (such as South Africa, China, and India) predicted to experience an increase of 78% in the number of cancer cases by 2030, and low HDI countries predicted to undergo a 93% increase over the same period. The study also revealed the following trends:

• Prostate cancer and female breast cancer incidence rates appear to be rising in most countries currently with medium, high, or very high levels of HDI.
• Stomach cancer and cervical cancer are predominantly decreasing in countries with medium, high, or very high levels of HDI, although for cervix cancer, there are a number of exceptions.
• In countries with high and very high HDI levels, lung cancer incidence rates tend to be decreasing in men, but increasing in women, though in a given country this is dependent on the current stage of the tobacco epidemic; while lung cancer is not a leading cancer in low HDI regions at present, it will become a leading cause of cancer unless tobacco smoking is effectively controlled in these areas.
• In 2008, almost 40% of the incident cases of cancer that occur globally occur in very high HDI countries, despite these regions containing just 15% of the world's population.

While the authors point out that their predictions are constrained by incomplete data on cancer incidence for many countries, particularly in the developing world, their results nonetheless provide a startling indicator of likely global cancer trends over the next few decades.

Dr Christopher Wild, IARC Director said: "This study reveals the dynamic nature of cancer patterns in a given region of the world over time. Countries must take account of the specific challenges they will face and prioritise targeted interventions to combat the projected increases in cancer burden via effective primary prevention strategies, early detection, and effective treatment programmes".

More information: Study online: www.thelancet.com/… 1-5/abstract

Journal reference: Lancet Oncology

Provided by Lancet