Global Burden of Cancer on the Rise: Implications for Cancer Prevention and Control
As the global burden of cancer grows, cancer control measures must be tailored to regional and national priorities, underscoring the need for high-quality cancer registries, according to Christopher P. Wild, PhD, Director of the International Agency for Research on Cancer in Lyon, France.
Cancer registration is a foundation of cancer control. Registries are the platform on which everything else should be built.— Christopher P. Wild, PhD
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Earlier this year, the United Nations General Assembly held the third high-level meeting on the prevention and control of noncommunicable diseases, which undertook a comprehensive review of the global and national progress achieved in preventing early death from heart and lung diseases, cancer, and diabetes. According to Dr. Wild, one of the focuses of the noncommunicable diseases agenda—and a departure from decades past—was recognition of the importance of cancer registries.
“Cancer registration is a foundation of cancer control,” he said at the 2018 World Cancer Congress in Kuala Lumpur, Malaysia.1 “Registries are the platform on which everything else should be built; they help us to describe the burden of cancer, so we can understand the scale of the challenge. They give us clues to understand what’s driving the patterns of cancer, so we can generate new hypotheses about etiology. They inform us about the type of care we need to provide for patients and survivors, and they help us evaluate interventions we put in place to reduce the cancer burden.”
Incidence, Mortality, and Prevalence
According to the 2018 GLOBOCAN database, the global cancer burden is predicted to rise to 18.1 million new cases, 9.6 million cancer deaths, and 43.8 million people living with cancer in 2018.2 The burden varies by region: almost half of the cancer incidence occurs in Asia, reflecting the large population base, but nearly one-quarter occurs in Europe, where just 9% of the world’s population resides, noted Dr. Wild.
About one-quarter of all cancers in women worldwide are breast cancers. The incidence of breast cancer in high-income countries is leveling off or even dropping, but in many other countries in transition, the incidence of breast cancer is rising steeply, said Dr. Wild. Meanwhile, the global incidence of lung cancer in women is climbing, reflecting the impact of the uptake of tobacco among women in many countries.
In men, lung and prostate cancers are the most common in terms of incidence and mortality. “We know almost nothing about the etiology of prostate cancer globally,” Dr. Wild noted. “Perhaps there’s a major opportunity to glean some understanding from the very high incidences in Africa, where prostate-specific antigen–based screening has not yet fully penetrated into national settings.”
Cancer is a disease of differences. It’s a global problem, but it’s very different by region and country. It is also a disease of inequality.— Christopher P. Wild, PhD
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Meanwhile, liver and stomach cancers have become critical players in terms of global cancer deaths among men; these cancers typically have a poor prognosis and often occur in countries unequipped to treat such aggressive tumors.
When cancer incidence is stratified according to the Human Development Index (see sidebar), there is a predominance of breast, colorectal, lung, and prostate cancers in regions with a high and very high Human Development Index, whereas the incidence of cervical, lip, oral cavity, and liver cancers becomes apparent in countries with a middle and low Human Development Index.
“Cancer is a disease of differences. It’s a global problem, but it’s very different by region and country,” noted Dr. Wild. “It is also a disease of inequality.” For example, a woman diagnosed with breast cancer in Australia or Western Europe has a high chance of survival compared with a woman with the same malignancy in parts of Asia or Africa.
Future Projections and Registry Availability
Cancer is a growing burden at all levels of human development, and the burden is greatest in the countries least able to meet the challenge in terms of cancer services.
Based on demographic changes, aging, and the growing world population, there is evidence that the number of new cases will grow from 18.1 million to 29.4 million between now and 2040.1 “This is 10 million extra cancer cases every year globally,” Dr. Wild emphasized. “This is a stunning figure, and we know it is coming. We have a responsibility to respond to it.”
When stratified by Human Development Index, high-quality registries are still very much skewed to the wealthier nations, but the International Agency for Research on Cancer and other global partners in the Global Initiative for Cancer Registry Development have been working toward improving the quality and coverage of cancer registries. As a result, population-based cancer registries are becoming more widespread.
“This is an extremely positive indication and a major step forward,” commented Dr. Wild. “We’re doing this by creating regional hubs of expertise in cancer registration, coordinated at a global level but with country leadership and a regional focus. However, he added, a major failing is in identifying financing for this vital activity, even in the face of its fundamental importance. “We struggle to find $15 million over 5 years for cancer registration, which would transform the basis on which the ministries of health could make sensible investments in cancer control. This, to me, is an anomaly,” he declared.
So, What Can We Do?
According to Dr. Wild, about half of cancers could be prevented by applying current knowledge and translating the existing knowledge about etiology into effective interventions. The majority of cancers have an environmental or lifestyle cause, so the potential for prevention is actually much higher, he said. But there is also a continuing need to study the causes of cancers for which an etiology is unknown, before attempting to lay a foundation for their prevention.
WHAT IS THE HUMAN DEVELOPMENT INDEX?
- The Human Development Index (HDI) is a statistical composite index of life expectancy, education, and per capita income indicators. These indicators are used to rank countries into tiers of human development.
- For example, a country scores a higher HDI when the lifespan is higher, the education level is higher, and the gross domestic product per capita is higher. Simply, the HDI can be viewed as an index of “potential” human development, focusing on whether people are able to “be” (well fed, sheltered, healthy) and “do” (work, learn through education, vote, participate in community life). Freedom of choice is a key factor.
- In the 2018 HDI rankings, Norway, Switzerland, and Australia ranked first, second, and third, respectively. The United States ranked 13, and the United Kingdom ranked 14.
Source: United Nations Development Programme: Human Development Reports (http://hdr.undp.org/en/content/human-development-index-hdi).
Prevention should also be adapted to the national or regional situation. The burden of cancer attributable to infection is about 15% globally, but 1 in 3 cancer cases in Sub-Saharan Africa is linked to a chronic infection, compared with just 1 in 30 in New Zealand, Australia, or North America. When stratified by cancers attributable to high body mass index, the picture is almost inverse, with a strong contribution from high-income countries. “Clearly, the prioritization has to be different,” he indicated.
In terms of primary prevention, he stressed the importance of hepatitis B and human papillomavirus vaccinations, and secondary prevention measures should focus on screening in high-incidence regions—particularly for cervical, breast, colorectal, and oral cancers—with timely treatment. “Mammography is really only applicable in places with a well-developed health service,” he cautioned. “One of the major challenges globally is to find an alternative to mammography that can be applied to screening and early detection of breast cancer in low- and middle-income countries.”
Further facets of essential cancer intervention and treatment should include comprehensive tobacco control measures and an emphasis on palliative care and pain control. “Cancer prevention takes time and also requires a lengthy political commitment,” Dr. Wild told his listeners. For example, the increased price of cigarettes and interventions against tobacco have impacted cigarette consumption enough to change lung cancer mortality rates in many countries; similarly, cervical cancer incidence and projected rates have declined due to effective screening. “This took decades, but the benefits are now being seen,” he added.
“We must recognize that patterns of cancer change over time with human development,” said Dr. Wild. “But a lot can be done now through prevention, early detection, and treatment, even in the face of limited resources.” ■
DISCLOSURE: Dr. Wild reported no conflicts of interest.
2. International Agency for Research on Cancer: Latest global cancer data. September 12, 2018. Available at https://www.iarc.fr/en/media-centre/pr/2018/pdfs/pr263_E.pdf. Accessed November 13, 2018.