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The evolution of cancer in ageing societies: An international perspective

Final Report Summary - CAN-EVOLUTION (The evolution of cancer in ageing societies: An international perspective)

This EU funded research project ‘Can-Evolution’ aimed to examine whether increases in life expectancy after cancer diagnosis have led to expansion of morbidity in various populations worldwide. The course of ageing in different countries varies, being partially influenced by the incidence and mortality of smoking-related cancers. Reduced smoking prevalence and hence mortality from smoking related cancers in particular and cancer and other chronic disease more generally in developed countries means further increases in life expectancy can be anticipated. The first aim of this project was to assess (a) whether there is an alternating cycle over time with regard to (healthy) life expectancy. In order to achieve this goal a trend analysis complemented with systematic assessment of the cross-country variation was performed to give insight into a possible transition model explaining the process of ageing in population with cancers. This is followed by an assessment of (b) the impact of major cancer sites such as breast or prostate cancers on healthy life expectancy in the 21st century, which formed the second aim of this project. Major breakthroughs in the treatment of these cancers have led to marked increases in survival. Conversely, it has come to the attention of many that most cancer treatments themselves impose health burdens on patients. Thus, greater prevalence of cancers with better prognosis will result in multiple moderate morbidity and disabilities that last for many years after the primary cancer diagnosis.

As a first step, the global burden of cancer was reviewed. This was done relative to other non-communicable diseases (NCDs) taking into account the changing global pattern in cancer incidence and mortality as well as in cancer risk factors. Worldwide, 55 million deaths occurred in 2011, of which almost two-thirds or 36 million deaths were the result of NCDs. Cancer now outranks deaths from coronary heart disease and from stroke as the leading cause of death worldwide. The dominant role of cancer is consistent with global socioeconomic transitions. From 1990 to 2010, communicable, maternal and neonatal, and nutritional deaths declined by 17 percent, but this decline was offset by a 30 percent increase in NCD-related deaths. The shift is largely driven by population growth and improved longevity; while NCD-related deaths have increased by 30 percent—from 27 to 34 million from 1990 and 2010—death rates have declined by 19 percent—from 646 to 520 per 100,000—over the same period. Cancer is an even larger component of the NCD burden in high or very high HDI countries. For example in Japan, cancer represents over 50 percent of all NCD deaths combined. In other 40 high income countries, age-adjusted cancer mortality rates are equal to, or exceed, those of cardiovascular disease (CVD) in premature mortality age ranges.

Using European data in collaboration with various prominent cancer epidemiologist we did a comprehensive overview of the most recent trends in incidence, during 1988-2010, in 26 countries, of four of the major cancers associated with tobacco smoking and also five major cancer types in Europe including breast, colon and rectum, prostate and corpus uteri. This was done to quantify the increase or the decrease in the morbidity burden from these cancers and also to look into the possible causes of such changes. For tobacco-related cancer, generally, the high rates among men have been declining, while the lower rates among women are increasing, resulting in convergence of the rates. Incidence of four common cancers in eastern and central European countries (prostate, postmenopausal breast, corpus uteri and colorectum) started to approach levels in northern and western Europe, where rates were already high in the past but levelled off in some countries in recent years. Increasing trends in incidence of the most common cancers, except stomach cancer, are bad news to public health but can largely be explained by well-known changes in society in the past decades. This suggests that current and future efforts in primary cancer prevention should not only remain focused on the further reduction of smoking but engage in the long-term efforts to retain healthy lifestyles.

The final step in this project was to look into the impact of these changes (cancer risk and mortality) on life expectancy and healthy life expectancy. Because of the importance of tobacco in cancer risk and (risk of death), we first assessed the impact of tobacco on mortality (by cause of death) and hence on life expectancy over time worldwide. Its impact varies greatly by countries, reducing life expectancy at age 40 by up to 22% for male in Hungary in the most recent period. Cancers especially that of the lung and upper aerodigestive tract contributed to a large proportion of the total smoking-related mortality. Yet this contribution highly varied by geographical location and time, depending on the country’s position within the smoking epidemic continuum. We also assessed the impact of breast cancer on healthy life expectancy over time worldwide, and observed a growing importance of breast cancer in all countries especially in countries where greatest achievement in decreasing mortality from other causes was found. All in all, we expected to observe in all countries, rich or poor, an increasing role of cancer – suggesting the urgent needs to improve cancer control strategies.

As a final result, this project has reached its potential to develop a theoretical framework to describe the relation between life expectancy and disability to many type-specific cancers and also other chronic diseases, which was the first in its field. The review done in this project will be published in the Disease and Control Priorities 3rd edition (http://www.dcp-3.org/) which will be used to promote and support the use of economic evaluation for priority setting at both global and national levels. The papers published (three additional papers are in preparation) will informed the research community of the global cancer burden. Finally, this project also contributed to sub-chapters of the global cancer atlas (http://www.cancer.org/aboutus/globalhealth/cancer-atlas-second-edition) that will inform larger research communities and also the lay audience with the aim to increase global awareness of cancer. The Cancer Atlas is a publication that is edited by the American Cancer Society and the IARC. It illustrates the latest available data and trends on the cancer epidemic, showing the prevalence of major risk factors, stages of development, and rates of different types of cancers by gender, income group, and region. Accessible for the layman but detailed enough for the expert, it examines the costs of the disease, both in terms of health care and commercial interests, and highlights the steps being taken to curb the epidemic, from research and screening to cancer control programs and health education.