The International Agency for Research on Cancer (IARC) has just published its latest estimates of the global burden of cancer.
The GLOBOCAN 2018 database, available online as part of IARC's Global Cancer Observatory, provides estimates of incidence and mortality in 185 countries and for 36 cancer types and all cancer sites combined.
An analysis of these results highlights the great geographical heterogeneity of cancer incidence, and the variations in the extent and profile of the disease between and within different regions of the world.
Global cancer burden: 18.1 million new cases
The global burden of cancer is estimated to reach 18.1 million new cases and 9.6 million deaths in 2018. One in five men and one in six women worldwide will develop cancer in their lifetime, and one in eight men and one in 11 women will die from the disease. Worldwide, the total number of people living with cancer within five years of diagnosis, known as five-year prevalence, is estimated at 43.8 million.
The increasing burden of cancer is due to a number of factors, including population growth and ageing, as well as changes in the prevalence of certain causes of cancer associated with social and economic development. This is particularly true in fast-growing economies, where there has been a shift from cancers associated with poverty and infection to cancers associated with lifestyles more typical of industrialized countries.
Decline in certain cancers
The effectiveness of prevention efforts may partly explain the observed decline in incidence rates for certain cancers, such as lung cancer (e.g. among men in Northern Europe and North America) and cervical cancer (in most regions other than sub-Saharan Africa). However, the new data show that most countries are still facing an increase in the absolute number of cases diagnosed and requiring treatment and care.
Global trends show that for men and women combined, nearly half of all new cases and more than half of all cancer deaths worldwide in 2018 occur in Asia - partly because the region concentrates nearly 60% of the world's population.
Europe accounts for 23.4% of the world's cancer cases and 20.3% of cancer deaths, but only 9.0% of the world's population. The Americas account for 13.3% of the world's population, but 21.0% of global incidence and 14.4% of mortality. In contrast to other regions of the world, the proportions of cancer deaths in Asia and Africa (57.3% and 7.3%, respectively) are higher than the proportions of incidence cases (48.4% and 5.8%, respectively), because these regions have a higher frequency of certain types of cancer associated with a poorer prognosis, and also higher mortality rates, in addition to limited access to diagnostic services and timely treatment in many countries.
Main types of cancer in 2018
Lung, female breast and colorectal cancers are the top three cancer types in terms of incidence, and rank in the top five in terms of mortality (first, fifth and second, respectively). Taken together, these three types of cancer account for a third of cancer incidence and mortality worldwide.
Lung cancer, and breast cancer in women, are the world's leading cancers in terms of the number of new cases: an estimated 2.1 million diagnoses of each of these cancers in 2018, representing around 11.6% of the total cancer incidence burden. Colorectal cancer (1.8 million cases, 10.2% of the total) is the third most frequently diagnosed cancer, followed by prostate cancer (1.3 million cases, 7.1% of the total), with stomach cancer in fifth place (1.0 million cases, 5.7% of the total).
Lung cancer is also responsible for the highest number of deaths (1.8 million deaths, or 18.4% of the total), due to its poor prognosis worldwide, followed by colorectal cancer (881,000 deaths, or 9.2% of the total), stomach cancer (783,000 deaths, 8.2%) and liver cancer (782,000 deaths, or 8.2% of the total). Female breast cancer is the fifth leading cause of death (627,000 deaths, or 6.6% of the total), with a relatively favourable prognosis, at least in developed countries.
Global trends by level of human development
For many cancers, overall incidence rates in high or very high HDI countries are generally 2 to 3 times higher than in low or medium HDI countries. However, differences in mortality rates between these two categories of countries are less significant, partly because countries with a lower HDI have a higher frequency of certain types of cancer associated with poorer survival, and partly because access to timely diagnosis and effective treatment is less frequent. For men, lung cancer comes first and prostate cancer second in both developed and developing countries. Among women, breast cancer incidence rates far exceed those of other cancers in both developed and developing countries, followed by colorectal cancer in developed countries and cervical cancer in developing countries.
Worldwide cancer trends by gender
Lung cancer is the most frequently diagnosed cancer in men (14.5% of the total in men and 8.4% in women) and the leading cause of cancer death in men (22.0%, or around one in five deaths), followed in incidence by prostate cancer (13.5%) and colorectal cancer (10.9%) in men, and in mortality by liver cancer (10.2%) and stomach cancer (9.5%). Breast cancer is the most frequently diagnosed cancer in women (24.2%, or around one in four of all new cancer cases diagnosed in women worldwide), and is the most common cancer in 154 of the 185 countries covered by GLOBOCAN 2018. Breast cancer is also the leading cause of cancer death in women (15.0%), followed by lung cancer (13.8%) and colorectal cancer (9.5%), which are also the third and second most common types of cancer in women, respectively. Cervical cancer ranks fourth in terms of incidence (6.6%) and mortality (7.5%).
Worrying rise in lung cancer among women
Lung cancer is one of the leading causes of death in both men and women, and is the leading cause of cancer death in women in 28 countries. The highest incidence rates among women are found in North America, Northern and Western Europe (notably Denmark and the Netherlands), China, Australia and New Zealand, with Hungary topping the list.
"Measures taken under the best practices of the WHO Framework Convention on Tobacco Control have been successful in reducing active smoking and preventing involuntary exposure to tobacco smoke in many countries," says Dr Freddie Bray, Head of the Cancer Surveillance Section at IARC. "However, as the smoking epidemic varies between different regions of the world as well as between men and women, our results underline the need to continue to implement effective and targeted tobacco control policies in all countries of the world."
"These new figures show that much remains to be done to address the alarming increase in the global burden of cancer, and that prevention must play a key role in this," according to Dr Christopher Wild, Director of IARC. "Effective prevention and early detection policies must be implemented urgently to complement treatment in the fight against this devastating disease worldwide."