SeriesCancer survival: global surveillance will stimulate health policy and improve equity
Introduction
In September, 2011, the UN General Assembly in New York held its first high-level meeting on non-communicable diseases (NCDs). The governments of 113 countries set new strategic objectives for worldwide control of these diseases. The declaration1 emphasised the need for wider research and better policy for the prevention and control of all NCDs, including cancer, because of their rapidly growing effect on public health, especially in developing countries.
In 2008, about 12·7 million people were diagnosed with cancer around the world, and 7·6 million people died from it. More than half (56%) of those who were diagnosed in 2008 and almost 64% of those who died from cancer were living in low-income and middle-income countries.2 In 2010, about 8 million people died from cancer, a 38% increase since 1990.3 Even conservative projections suggest that more than 20 million people will be diagnosed with cancer every year by 2030, with more than 13 million cancer deaths.4 The increase in the number of patients with cancer will arise mainly from population growth and ageing of the population, but in many countries the risk of developing cancer at a given age (age-specific risk) will also rise. All three factors will affect poor countries more than rich ones. Without global policy initiatives, the disparity between the growing cancer burden and the capacity of poorer countries to deal with it can be expected to widen.
After the World Health Assembly in 2012, the governments of 119 countries unanimously agreed a set of 25 indicators and a voluntary global target to reduce premature deaths in people aged 30–69 years from all NCDs by 25% by 2025.5 This target would represent a reduction of about 1·5 million from the predicted 6 million premature cancer deaths each year by 2025. Achievement of this target will need more effective prevention, to reduce incidence, and more effective health systems, to improve survival.
Only population-based cancer registries can indicate whether these two requirements are being met. In 2010, however, WHO assessed the capacity for prevention and control of NCD in 185 countries. Less than half (48%) even had national reporting of mortality. Population-based cancer registries were active in just 17% of low-income countries and 79% of high-income countries, but barely a third (36%) had published a report in the previous 3 years.6 Only 21% of the world's population was covered by cancer registration in 2006.7 At a global level, therefore, reliable and up-to-date information on cancer incidence, mortality, and survival remains scarce.
In this Series paper I cover the need for investment in cancer control, the role of health systems, and the public health usefulness of trends and inequalities in cancer survival. I also cover estimation of the proportion of patients with cancer in a given population who can be deemed to have been cured, and avoidable premature deaths arising from inequalities in survival, before addressing the need for continuous global surveillance of cancer survival as one of the metrics for improvement of cancer control.
Section snippets
Investing in cancer control
Prevention will always be preferable to cure, especially for diseases with such high morbidity and lethality. When the causes are known, however, the latency between exposure and disease for many cancers is measured in decades, and for about half of all cancers the causes are still unknown. For primary prevention, long-term investment is needed to reduce age-specific cancer risks for future populations, but research is under-funded. The US National Cancer Institute is the largest cancer
Health systems, cancer survival, and equity
The millions of cancer patients who will be diagnosed every year for the foreseeable future need access to optimum treatment, wherever they live, to improve their chances of survival. The Universal Declaration of Human Rights (Article 25) states: “Everyone has the right to a standard of living adequate for the health and well-being of himself and of his family, including food, clothing, housing and medical care and necessary social services, and the right to security in the event of
Variation in survival
There is huge global inequity in access to cancer treatment. For example, radiotherapy can cure some cancers and is a crucial component of therapy for up to half of all cancers; however, although 56% of cancer patients live in low-income and middle-income countries, these countries have only 30% of the world's radiotherapy facilities. 30 countries in Africa and Asia do not have a single radiotherapy machine.18 Within Europe, variation in cancer treatment is wide,19 and variation in survival is
Useful or futile?
Is it useful to identify differences in cancer survival between countries, between regions within a country, or between populations defined by racial or ethnic group or socioeconomic status? Does it have any effect on health policy or the public, especially if the countries being compared have widely different economic development, some of them extremely poor, others with civil conflicts?
Population-based survival is an estimate of the probability of survival after the background mortality that
Cancer control plans
The availability of systematic information on international differences and trends in cancer survival will challenge the myth, prevalent in many countries,17 that cancer is uniformly fatal. When members of the public see that people can survive cancer, this damaging misconception can be corrected, and more patients will be prompted to seek and complete treatment. This aim is one of the goals of the World Cancer Declaration (panel 1).
Equally, international comparisons can challenge the
Inequalities in survival and avoidable premature deaths
Equal treatment for a given cancer should yield equal outcome, irrespective of race,64 geography, or socioeconomic status.65 Racial, ethnic, and socioeconomic differences in survival reflect differences in access to the best health services for minority populations, whether for black people in the USA,66 Aboriginal and Torres Strait Islander people in Australia,67 or Māori in New Zealand.68
The wider effect on public health of cancer survival disparities can contribute to the formulation of
The proportion of patients who are cured
Identification of individual cancer patients who might be judged clinically cured is difficult. In the public-health context, however, the proportion of all cancer patients in the population who can be regarded as cured can be estimated from the point where a curve of relative (or net) survival reaches a plateau. This point indicates that, as a group, the patients who have survived up to that time after cancer diagnosis no longer have significant excess mortality over that of the general
Global surveillance of cancer survival
At the World Cancer Congress in Geneva in 2008, the Union for International Cancer Control (UICC) called for 11 ambitious goals to be achieved by 2020, and updated the World Cancer Declaration17 to include: “there will be major improvements in cancer survival…in all countries”. The UICC is committed to providing progress reports every 2 years. Global surveillance of cancer survival will support several of the goals in the UICC World Cancer Declaration (panel 1).
Reliable information on global
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