Overview of Geographical Diversity
The diversity in cancer profiles in different world areas signifies that both regional cooperation and local, evidence-based interventions are needed in the fight against cancer.
There are striking geographic differences in the incidence and mortality of different cancer types in different world regions. This global diversity reflects both the presence of local risk factors for specific cancers, and the extent to which effective cancer control measures have been implemented. Much of the observed variation in recorded incidence rates of different cancer types in different registry populations can be ascribed to lifestyle and environmental factors. (Figure 1)
Such marked international variability supports the critical role of cancer prevention as a means to reduce the future cancer burden. Although specific causes remain unknown for many cancers, where measured, about two-fifths of cancers diagnosed today are potentially avoidable. Prevention measures include eliminating exposure to known lifestyle and environmental risk factors, including tobacco and alcohol, dietary factors, excess body weight, and UV radiation, and increasing resistance to infection by vaccination. However, the proportion of cancer cases avoidable—overall and for specific risk factors—substantially varies by region. For example, infection accounts for 30–50% of all cases in sub-Saharan Africa, whereas this proportion is only 3–5% in Europe and North America.
Cancer varies between different populations, and every type is rare in some part of the world. Many specific causes are now known (to explain these differences), but a large proportion of global variation for common cancers remains unexplained.
The most frequently diagnosed cancers and leading causes of cancer death at the national level reflect the major risk factors in the population and the average prognosis of the major cancers observed. (Map 1, 2) Certain cancers dominate the global landscape, particularly in women: female breast cancer is the most frequent cancer in four-fifths of the world’s nations, with cervical cancer ranking most frequent in the majority of remaining countries, particularly in sub-Saharan Africa. The mortality profile among women is slightly more heterogeneous, with lung cancer also a leading cause of death.
Among men, there is considerable international diversity in the leading cancer types, with around 10 different cancers as the most commonly diagnosed cancer or leading cause of cancer death. Prostate, lung, and liver cancer are major cancers in men, although other cancers dominate in some regions (lip and oral cavity in South Asia and Kaposi sarcoma in Eastern Africa). Nevertheless, lung cancer is the leading cause of cancer death among men in over half of the world’s countries.
Quote:
Peto J. Cancer epidemiology in the last century and the next decade. Nature. 2001;411: 390–395.
Most commonly diagnosed cancers:
Ferlay J, Ervik M, Lam F, et al. Global Cancer Observatory: Cancer Today. Lyon, France: IARC. Available from: https://gco.iarc.fr/today.
Text:
Bray F, Ferlay J, Laversanne M, et al. Cancer Incidence in Five Continents: Inclusion criteria, highlights from Volume X and the global status of cancer registration. Int J Cancer. 2015 Nov 1;137(9):2060–71.
Bray F, Soerjomataram I. Population attributable fractions continue to unmask the power of prevention. Br J Cancer. 2018 Apr;118(8):1031–1032.
Plummer M, de Martel C, Vignat J, Ferlay J, Bray F, Franceschi S. Global burden of cancers attributable to infections in 2012: a synthetic analysis. Lancet Glob Health. 2016;4(9):e609–16. (see http://gco.iarc.fr/causes/infections/home)
Map 1 and 2:
Ferlay J, Ervik M, Lam F, et al. Global Cancer Observatory: Cancer Today. Lyon, France: IARC. Available from: https://gco.iarc.fr/today.
Figure 1:
Bray F, Colombet M, Mery L, Piñeros M, Znaor A, Zanetti R and Ferlay J, editors (2017) Cancer Incidence in Five Continents, Vol. XI . Lyon: IARC. Available from: http://ci5.iarc.fr.
Explore Related Topics
This figure cannot be displayed at mobile resolutions.
To view this figure, please visit the desktop version of this website or download the PDF file of the book chapter.